From: Hugo Villeneuve hvilleneuve@dimonoff.com
The sc16is7xx_config_rs485() function is called only for the second port (index 1, channel B), causing initialization problems for the first port.
For the sc16is7xx driver, port->membase and port->mapbase are not set, and their default values are 0. And we set port->iobase to the device index. This means that when the first device is registered using the uart_add_one_port() function, the following values will be in the port structure: port->membase = 0 port->mapbase = 0 port->iobase = 0
Therefore, the function uart_configure_port() in serial_core.c will exit early because of the following check: /* * If there isn't a port here, don't do anything further. */ if (!port->iobase && !port->mapbase && !port->membase) return;
Typically, I2C and SPI drivers do not set port->membase and port->mapbase.
The max310x driver sets port->membase to ~0 (all ones). By implementing the same change in this driver, uart_configure_port() is now correctly executed for all ports.
Fixes: dfeae619d781 ("serial: sc16is7xx") Cc: stable@vger.kernel.org # 6.1.x Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Lech Perczak lech.perczak@camlingroup.com Tested-by: Lech Perczak lech.perczak@camlingroup.com --- drivers/tty/serial/sc16is7xx.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 2e7e7c409cf2..8ae2afc76a9b 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1436,6 +1436,7 @@ static int sc16is7xx_probe(struct device *dev, s->p[i].port.fifosize = SC16IS7XX_FIFO_SIZE; s->p[i].port.flags = UPF_FIXED_TYPE | UPF_LOW_LATENCY; s->p[i].port.iobase = i; + s->p[i].port.membase = (void __iomem *)~0; s->p[i].port.iotype = UPIO_PORT; s->p[i].port.uartclk = freq; s->p[i].port.rs485_config = sc16is7xx_config_rs485;
On Tue, Jul 25, 2023 at 10:23:33AM -0400, Hugo Villeneuve wrote:
From: Hugo Villeneuve hvilleneuve@dimonoff.com
The sc16is7xx_config_rs485() function is called only for the second port (index 1, channel B), causing initialization problems for the first port.
For the sc16is7xx driver, port->membase and port->mapbase are not set, and their default values are 0. And we set port->iobase to the device index. This means that when the first device is registered using the uart_add_one_port() function, the following values will be in the port structure: port->membase = 0 port->mapbase = 0 port->iobase = 0
Therefore, the function uart_configure_port() in serial_core.c will exit early because of the following check: /* * If there isn't a port here, don't do anything further. */ if (!port->iobase && !port->mapbase && !port->membase) return;
Typically, I2C and SPI drivers do not set port->membase and port->mapbase.
The max310x driver sets port->membase to ~0 (all ones). By implementing the same change in this driver, uart_configure_port() is now correctly executed for all ports.
Fixes: dfeae619d781 ("serial: sc16is7xx")
That commit is in a very old 3.x release.
Cc: stable@vger.kernel.org # 6.1.x
But you say this should only go to 6.1.y? Why? What is wrong with the older kernels?
Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Lech Perczak lech.perczak@camlingroup.com Tested-by: Lech Perczak lech.perczak@camlingroup.com
drivers/tty/serial/sc16is7xx.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 2e7e7c409cf2..8ae2afc76a9b 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1436,6 +1436,7 @@ static int sc16is7xx_probe(struct device *dev, s->p[i].port.fifosize = SC16IS7XX_FIFO_SIZE; s->p[i].port.flags = UPF_FIXED_TYPE | UPF_LOW_LATENCY; s->p[i].port.iobase = i;
s->p[i].port.membase = (void __iomem *)~0;
That's a magic value, some comment should be added here to explain why setting all bits is ok. Why does this work exactly? You only say that the max310x driver does this, but not why it does this at all.
confused,
greg k-h
On Mon, 31 Jul 2023 17:52:26 +0200 Greg KH gregkh@linuxfoundation.org wrote:
On Tue, Jul 25, 2023 at 10:23:33AM -0400, Hugo Villeneuve wrote:
From: Hugo Villeneuve hvilleneuve@dimonoff.com
The sc16is7xx_config_rs485() function is called only for the second port (index 1, channel B), causing initialization problems for the first port.
For the sc16is7xx driver, port->membase and port->mapbase are not set, and their default values are 0. And we set port->iobase to the device index. This means that when the first device is registered using the uart_add_one_port() function, the following values will be in the port structure: port->membase = 0 port->mapbase = 0 port->iobase = 0
Therefore, the function uart_configure_port() in serial_core.c will exit early because of the following check: /* * If there isn't a port here, don't do anything further. */ if (!port->iobase && !port->mapbase && !port->membase) return;
Typically, I2C and SPI drivers do not set port->membase and port->mapbase.
The max310x driver sets port->membase to ~0 (all ones). By implementing the same change in this driver, uart_configure_port() is now correctly executed for all ports.
Fixes: dfeae619d781 ("serial: sc16is7xx")
That commit is in a very old 3.x release.
Cc: stable@vger.kernel.org # 6.1.x
But you say this should only go to 6.1.y? Why? What is wrong with the older kernels?
Hi Greg, I have read (and reread a couple of times) Documentation/process/stable-kernel-rules.rst to try to understand how to format the tags, but unfortunately it doesn't contain "Everything you ever wanted to know about Linux -stable releases" as the title claims :)
In particular, it doesn't explain or advise which older version we should target, that is why since I was not sure I specified 6.1.y because I could test it properly, but not v3.x.
Maybe it would be best to simply drop for now all the "Cc: stable@vger.kernel.org" tags for this series, and following Option 2, I send an email to stable@vger.kernel.org once the patches have been merged to Linus' tree?
Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Lech Perczak lech.perczak@camlingroup.com Tested-by: Lech Perczak lech.perczak@camlingroup.com
drivers/tty/serial/sc16is7xx.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 2e7e7c409cf2..8ae2afc76a9b 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1436,6 +1436,7 @@ static int sc16is7xx_probe(struct device *dev, s->p[i].port.fifosize = SC16IS7XX_FIFO_SIZE; s->p[i].port.flags = UPF_FIXED_TYPE | UPF_LOW_LATENCY; s->p[i].port.iobase = i;
s->p[i].port.membase = (void __iomem *)~0;That's a magic value, some comment should be added here to explain why setting all bits is ok. Why does this work exactly? You only say that the max310x driver does this, but not why it does this at all.
I do not understand, because my commit log message is quite long and, it seems to me, well documenting why this works the way it does when calling uart_configure_port() in serial_core.c?
I say that the max310x driver also does this, because there is also no comment in the max310x driver for using the (void __iomem *)~0; construct. I also located the original commit message for the max310x driver but no comments were usefull there also.
So, what about adding this comment:
/* * Use all ones as membase to make sure uart_configure_port() in * serial_core.c does not abort for SPI/I2C devices where the * membase address is not applicable. */ s->p[i].port.membase = (void __iomem *)~0;
Also, keep in mind that in the original discussion about that patch, there was the following comment from Ilpo Järvinen:
------ This changelog was really well describing the problem! :-) Yeah, some other solution should be devised. Maybe we should add another .iotype for thse kind of devices. But I'm fine with this for this fix. After editing the changelog, feel free to add: Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com ------
If wou want, I could also add the same comment to the max310 driver?
Hugo.
On Tue, Aug 01, 2023 at 01:16:55PM -0400, Hugo Villeneuve wrote:
On Mon, 31 Jul 2023 17:52:26 +0200 Greg KH gregkh@linuxfoundation.org wrote:
On Tue, Jul 25, 2023 at 10:23:33AM -0400, Hugo Villeneuve wrote:
From: Hugo Villeneuve hvilleneuve@dimonoff.com
The sc16is7xx_config_rs485() function is called only for the second port (index 1, channel B), causing initialization problems for the first port.
For the sc16is7xx driver, port->membase and port->mapbase are not set, and their default values are 0. And we set port->iobase to the device index. This means that when the first device is registered using the uart_add_one_port() function, the following values will be in the port structure: port->membase = 0 port->mapbase = 0 port->iobase = 0
Therefore, the function uart_configure_port() in serial_core.c will exit early because of the following check: /* * If there isn't a port here, don't do anything further. */ if (!port->iobase && !port->mapbase && !port->membase) return;
Typically, I2C and SPI drivers do not set port->membase and port->mapbase.
The max310x driver sets port->membase to ~0 (all ones). By implementing the same change in this driver, uart_configure_port() is now correctly executed for all ports.
Fixes: dfeae619d781 ("serial: sc16is7xx")
That commit is in a very old 3.x release.
Cc: stable@vger.kernel.org # 6.1.x
But you say this should only go to 6.1.y? Why? What is wrong with the older kernels?
Hi Greg, I have read (and reread a couple of times) Documentation/process/stable-kernel-rules.rst to try to understand how to format the tags, but unfortunately it doesn't contain "Everything you ever wanted to know about Linux -stable releases" as the title claims :)
In particular, it doesn't explain or advise which older version we should target, that is why since I was not sure I specified 6.1.y because I could test it properly, but not v3.x.
If you think this fixes an issue back to 3.x, then just leave it at that, there's no need to have to test all of these. If when I apply the patch to the stable trees, and it does not go back to all of the active versions specified by Fixes: then you will get an email saying so and can handle it then if you want to.
Maybe it would be best to simply drop for now all the "Cc: stable@vger.kernel.org" tags for this series, and following Option 2, I send an email to stable@vger.kernel.org once the patches have been merged to Linus' tree?
That will just mean more work for both of us, leave it as is, just drop the "# 6.1.x" portion please.
Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Lech Perczak lech.perczak@camlingroup.com Tested-by: Lech Perczak lech.perczak@camlingroup.com
drivers/tty/serial/sc16is7xx.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 2e7e7c409cf2..8ae2afc76a9b 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1436,6 +1436,7 @@ static int sc16is7xx_probe(struct device *dev, s->p[i].port.fifosize = SC16IS7XX_FIFO_SIZE; s->p[i].port.flags = UPF_FIXED_TYPE | UPF_LOW_LATENCY; s->p[i].port.iobase = i;
s->p[i].port.membase = (void __iomem *)~0;That's a magic value, some comment should be added here to explain why setting all bits is ok. Why does this work exactly? You only say that the max310x driver does this, but not why it does this at all.
I do not understand, because my commit log message is quite long and, it seems to me, well documenting why this works the way it does when calling uart_configure_port() in serial_core.c?
I say that the max310x driver also does this, because there is also no comment in the max310x driver for using the (void __iomem *)~0; construct. I also located the original commit message for the max310x driver but no comments were usefull there also.
So, what about adding this comment:
/*
- Use all ones as membase to make sure uart_configure_port() in
- serial_core.c does not abort for SPI/I2C devices where the
- membase address is not applicable.
*/ s->p[i].port.membase = (void __iomem *)~0;
Yes, that would be good, thank you.
If wou want, I could also add the same comment to the max310 driver?
Yes please.
thanks,
greg k-h
On Thu, 3 Aug 2023 09:54:37 +0200 Greg KH gregkh@linuxfoundation.org wrote:
On Tue, Aug 01, 2023 at 01:16:55PM -0400, Hugo Villeneuve wrote:
On Mon, 31 Jul 2023 17:52:26 +0200 Greg KH gregkh@linuxfoundation.org wrote:
On Tue, Jul 25, 2023 at 10:23:33AM -0400, Hugo Villeneuve wrote:
From: Hugo Villeneuve hvilleneuve@dimonoff.com
The sc16is7xx_config_rs485() function is called only for the second port (index 1, channel B), causing initialization problems for the first port.
For the sc16is7xx driver, port->membase and port->mapbase are not set, and their default values are 0. And we set port->iobase to the device index. This means that when the first device is registered using the uart_add_one_port() function, the following values will be in the port structure: port->membase = 0 port->mapbase = 0 port->iobase = 0
Therefore, the function uart_configure_port() in serial_core.c will exit early because of the following check: /* * If there isn't a port here, don't do anything further. */ if (!port->iobase && !port->mapbase && !port->membase) return;
Typically, I2C and SPI drivers do not set port->membase and port->mapbase.
The max310x driver sets port->membase to ~0 (all ones). By implementing the same change in this driver, uart_configure_port() is now correctly executed for all ports.
Fixes: dfeae619d781 ("serial: sc16is7xx")
That commit is in a very old 3.x release.
Cc: stable@vger.kernel.org # 6.1.x
But you say this should only go to 6.1.y? Why? What is wrong with the older kernels?
Hi Greg, I have read (and reread a couple of times) Documentation/process/stable-kernel-rules.rst to try to understand how to format the tags, but unfortunately it doesn't contain "Everything you ever wanted to know about Linux -stable releases" as the title claims :)
In particular, it doesn't explain or advise which older version we should target, that is why since I was not sure I specified 6.1.y because I could test it properly, but not v3.x.
If you think this fixes an issue back to 3.x, then just leave it at that, there's no need to have to test all of these. If when I apply the patch to the stable trees, and it does not go back to all of the active versions specified by Fixes: then you will get an email saying so and can handle it then if you want to.
Maybe it would be best to simply drop for now all the "Cc: stable@vger.kernel.org" tags for this series, and following Option 2, I send an email to stable@vger.kernel.org once the patches have been merged to Linus' tree?
That will just mean more work for both of us, leave it as is, just drop the "# 6.1.x" portion please.
Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Lech Perczak lech.perczak@camlingroup.com Tested-by: Lech Perczak lech.perczak@camlingroup.com
drivers/tty/serial/sc16is7xx.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 2e7e7c409cf2..8ae2afc76a9b 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1436,6 +1436,7 @@ static int sc16is7xx_probe(struct device *dev, s->p[i].port.fifosize = SC16IS7XX_FIFO_SIZE; s->p[i].port.flags = UPF_FIXED_TYPE | UPF_LOW_LATENCY; s->p[i].port.iobase = i;
s->p[i].port.membase = (void __iomem *)~0;That's a magic value, some comment should be added here to explain why setting all bits is ok. Why does this work exactly? You only say that the max310x driver does this, but not why it does this at all.
I do not understand, because my commit log message is quite long and, it seems to me, well documenting why this works the way it does when calling uart_configure_port() in serial_core.c?
I say that the max310x driver also does this, because there is also no comment in the max310x driver for using the (void __iomem *)~0; construct. I also located the original commit message for the max310x driver but no comments were usefull there also.
So, what about adding this comment:
/*
- Use all ones as membase to make sure uart_configure_port() in
- serial_core.c does not abort for SPI/I2C devices where the
- membase address is not applicable.
*/ s->p[i].port.membase = (void __iomem *)~0;
Yes, that would be good, thank you.
If wou want, I could also add the same comment to the max310 driver?
Yes please.
Hi Greg, I will send a separate patch specifically for this.
Thank you, Hugo.
linux-stable-mirror@lists.linaro.org
-
Greg KH -
Hugo Villeneuve