From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Schocher Date: Fri, 10 Apr 2020 10:49:08 +0200 Subject: Calling i2c set speed twice for i2c_mux_bus In-Reply-To: References: Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hello Michal, Am 10.04.2020 um 08:46 schrieb Michal Simek: > Hi Heiko, > > On 10. 04. 20 7:11, Heiko Schocher wrote: >> Hello Michal, >> >> Am 09.04.2020 um 16:03 schrieb Michal Simek: >>> Hi Heiko and Simon, >>> >>> I have find out one bug in i2c class. I am using zcu104 revC board which >>> has dts in mainline where i2c1 has i2c mux with some channels. >>> In DT clock-frequency = <400000>; is specified and it is read in >>> i2c_post_probe(). But i2c_mux_bus_drv is also UCLASS_I2C which means >>> that post probe is called for it too. And because clock-frequency >>> property is not there default 100k is used. >>> >>> I think that is bug and should be fixed. >>> Heiko: Are you aware about this issue? >> >> No :-( >> >> The question is, is this a bug? > > I have never seen clock-frequency property in i2c mux bus node. Also I > have looked at linux dt binding docs and nothing like that is specified > there. From quick look also pca954x driver is not reading it. Indeed. >> Should a i2c bus behind a mux not be able to set his own speed? > > Not sure if that make sense but Linux will likely ignore it. I am not > saying it doesn't make sense but I haven't seen this feature. Ok. >> But may as a feature (or bugfix?) if "clock-frequency" is not there, >> use the speed of the parent bus...? > > I was thinking about this too. > just c&p quick implementation would look like this. Because it is > i2c->i2c_mux->i2c. But maybe there is a better way how to do it. > > diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c > index 2aa3efe8aaa0..982c467deba3 100644 > --- a/drivers/i2c/i2c-uclass.c > +++ b/drivers/i2c/i2c-uclass.c > @@ -640,9 +640,21 @@ static int i2c_post_probe(struct udevice *dev) > { > #if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA) > struct dm_i2c_bus *i2c = dev_get_uclass_priv(dev); > + int parent_speed = I2C_SPEED_STANDARD_RATE; > + > + if (dev->parent && > + device_get_uclass_id(dev->parent) == UCLASS_I2C_MUX && > + dev->parent->parent && > + device_get_uclass_id(dev->parent->parent) == UCLASS_I2C) { > + struct dm_i2c_bus *i2c_parent; > + > + i2c_parent = dev_get_uclass_priv(dev->parent->parent); > + parent_speed = i2c_parent->speed_hz; > + /* Not sure if make sense to check that parent_speed is > not 0 */ I think this check is not needed. > + } > > i2c->speed_hz = dev_read_u32_default(dev, "clock-frequency", > - I2C_SPEED_STANDARD_RATE); > + parent_speed); Wow, a big if ... may this is clearer (not compile tested)? udevice *parent = dev_get_parent(dev); if (parent && device_get_uclass_id(parent) == UCLASS_I2C_MUX) { udevice *parent2 = dev_get_parent(parent); if (parent2 && device_get_uclass_id(parent2) == UCLASS_I2C) { struct dm_i2c_bus *i2cp = dev_get_uclass_priv(parent2); parent_speed = i2cp->speed_hz; } } but Simon has a deeper DM knowledge, may there is a better approach. > > return dm_i2c_set_bus_speed(dev, i2c->speed_hz); > #else > > Thanks, > Michal Thanks! bye, Heiko -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-52 Fax: +49-8142-66989-80 Email: hs at denx.de