From: Boris Brezillon boris.brezillon@collabora.com Date: Thu, Jun 06, 2019 at 18:35:40
On Thu, 6 Jun 2019 17:16:55 +0000 Vitor Soares Vitor.Soares@synopsys.com wrote:
From: Boris Brezillon boris.brezillon@collabora.com Date: Thu, Jun 06, 2019 at 15:18:44
On Thu, 6 Jun 2019 16:00:01 +0200 Vitor Soares Vitor.Soares@synopsys.com wrote:
Currently the I3C framework limits SCL frequency to FM speed when dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
The core was also not accounting for I3C speed limitations when operating in mixed slow mode and was erroneously using FM+ speed as the max I2C speed when operating in mixed fast mode.
Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure") Signed-off-by: Vitor Soares vitor.soares@synopsys.com Cc: Boris Brezillon bbrezillon@kernel.org Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org
Changes in v2: Enhance commit message Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint Add dev_warn() in case user-defined i3c rate lower than i2c rate.
drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 48 insertions(+), 13 deletions(-)
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 5f4bd52..8cd5824 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus) up_read(&bus->lock); } +static struct i3c_master_controller * +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus) +{
- return container_of(i3cbus, struct i3c_master_controller, bus);
+}
static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev) { return container_of(dev, struct i3c_master_controller, dev); @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = { .groups = i3c_masterdev_groups, }; -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode) +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
unsigned long max_i2c_scl_rate){
- i3cbus->mode = mode;
- if (!i3cbus->scl_rate.i3c)
i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
- struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
- if (!i3cbus->scl_rate.i2c) {
if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;elsei3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
- i3cbus->mode = mode;
- switch (i3cbus->mode) {
- case I3C_BUS_MODE_PURE:
if (!i3cbus->scl_rate.i3c)i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;break;- case I3C_BUS_MODE_MIXED_FAST:
if (!i3cbus->scl_rate.i3c)i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;if (!i3cbus->scl_rate.i2c)i3cbus->scl_rate.i2c = max_i2c_scl_rate;break;- case I3C_BUS_MODE_MIXED_SLOW:
if (!i3cbus->scl_rate.i2c)i3cbus->scl_rate.i2c = max_i2c_scl_rate;if (!i3cbus->scl_rate.i3c ||i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;break;- default:
return -EINVAL;
- if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
dev_warn(&master->dev,"i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);- if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&i3cbus->mode != I3C_BUS_MODE_PURE)If you are so strict, there's clearly no point exposing an i2c-scl-hz property. I'm still not convinced having an i2c rate that's slower than what the I2C/I3C spec defines as the *typical* rate is a bad thing,
I'm not been strictive, I just inform the user about that case.
Then use dev_debug() and don't make the trace conditional on i2c_rate != typical_rate.
Ok. I will change to dev_debug().
The only case where we should warn users is i2c_rate > typical_rate, because that might lead to malfunctions.
Can you explain why?
just like I'm not convinced having an I3C rate that's slower than the I2C one is a problem (it's definitely a weird situation, but there's nothing preventing that in the spec).
You agree that there is no point for case where i3c rate < i2c rate yet you are not convinced.
I didn't say that, there might be use cases where one wants to slow down the I3C bus to be able to probe it or use a slower rate when things do not work properly. It's rather unlikely to happen, but I don't think it deserves a warning message when that's the case.
Do you thing that will be users for this case?
Anyway, this isn't a high requirement for me. The all point of this patch is to introduce the limited bus configuration.
And yet, you keep insisting (and ignoring my feedback) on that point :P.
If you check the previous version you see that I'm trying to follow 😉 I will change the dev_warn() to dev_dbg() due the trace is indeed too much.
Best regards, Vitor Soares