From: Boris Brezillon boris.brezillon@collabora.com Date: Wed, Jun 12, 2019 at 07:15:33
On Tue, 11 Jun 2019 16:06:43 +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 v3: Change dev_warn() to dev_dbg()
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..f8e580e 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_dbg(&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)dev_dbg(&master->dev,"i2c-scl-hz=%ld not defined according MIPI I3C spec\n",i3cbus->scl_rate.i2c);Again, that's not what I suggested, so I'll write it down:
dev_dbg(&master->dev, "i2c-scl = %ld Hz i3c-scl = %ld Hz\n", i3cbus->scl_rate.i2c, i3cbus->scl_rate.i3c);
I'm not ok with that change. The reasons are: i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c is an abnormal use case. As discuss early it can be cause by a wrong DT definition or just for testing purposes.
i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE && i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE, the MIPI I3C Spec v1.0 clearly says that all I2C devices on the bus shall have a LVR register and thus support FM or FM+ modes. By definition a FM bus works at 400kHz and a FM+ bus 1MHz. And for slaves, a FM device works up to 400kHz and a FM+ device works up to 1MHz respectively.
Apart of that, if the I2C device support you can use a custom higher or lower rate, yet not defined according MIPI I3C spec.
dev_dbg() is not printed by default, so it's just fine to have a trace that prints the I3C and I2C rate unconditionally.
I'm ok to change the way that user is notified and I think that is here the problem. Maybe the best is to change the first dev_dbg() to dev_warn() and the second dev_info().
/* * I3C/I2C frequency may have been overridden, check that user-provided * values are not exceeding max possible frequency. @@ -1966,9 +2000,6 @@ of_i3c_master_add_i2c_boardinfo(struct i3c_master_controller *master, /* LVR is encoded in reg[2]. */ boardinfo->lvr = reg[2];
- if (boardinfo->lvr & I3C_LVR_I2C_FM_MODE)
master->bus.scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;- list_add_tail(&boardinfo->node, &master->boardinfo.i2c); of_node_get(node);
@@ -2417,6 +2448,7 @@ int i3c_master_register(struct i3c_master_controller *master, const struct i3c_master_controller_ops *ops, bool secondary) {
- unsigned long i2c_scl_rate = I3C_BUS_I2C_FM_PLUS_SCL_RATE; struct i3c_bus *i3cbus = i3c_master_get_bus(master); enum i3c_bus_mode mode = I3C_BUS_MODE_PURE; struct i2c_dev_boardinfo *i2cbi;
@@ -2466,9 +2498,12 @@ int i3c_master_register(struct i3c_master_controller *master, ret = -EINVAL; goto err_put_dev; }
if (i2cbi->lvr & I3C_LVR_I2C_FM_MODE)i2c_scl_rate = I3C_BUS_I2C_FM_SCL_RATE;
- ret = i3c_bus_set_mode(i3cbus, mode);
- ret = i3c_bus_set_mode(i3cbus, mode, i2c_scl_rate); if (ret) goto err_put_dev;