[AMD Official Use Only - General] Hi , Thanks for the patch > -----Original Message----- > From: carsten.haitzler@foss.arm.com > Sent: Friday, November 25, 2022 5:21 PM > To: michal.simek@xilinx.com; shubhrajyoti.datta@xilinx.com; linux-arm- > kernel@lists.infradead.org; linux-i2c@vger.kernel.org; linux- > kernel@vger.kernel.org > Cc: torvalds@linux-foundation.org > Subject: [PATCH] i2c: cadence: Fix regression with bus recovery > > CAUTION: This message has originated from an External Source. Please use > proper judgment and caution when opening attachments, clicking links, or > responding to this email. > > > From: Carsten Haitzler > > Commit "i2c: cadence: Add standard bus recovery support" breaks for i2c > devices that have no pinctrl defined. There is no requirement for this to exist > in the DT. This has worked perfectly well without this before in at least 1 real > usage case on hardware (Mali Komeda DPU, Cadence i2c to talk to a tda99xx > phy). Adding the requirement to have pinctrl set up in the device tree (or > otherwise be found) is a regression where the whole i2c device is lost > entirely (in this case dropping entire devices which then leads to the drm > display stack unable to find the phy for display output, thus having no drm > display device and so on down the chain). > > This converts the above commit to an enhancement if pinctrl can be found > for the i2c device, providing a timeout on read with recovery, but if not, do > what used to be done rather than a fatal loss of a device. > > This restores the mentioned display devices to their working state again. > > Fixes: 58b924241d0a ("i2c: cadence: Add standard bus recovery support") > Signed-off-by: Carsten Haitzler > --- > Note: This issue was discovered during the porting of the linux kernel on > Morello [1]. > > [1] > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit. > morello- > project.org%2Fmorello%2Fkernel%2Flinux&data=05%7C01%7Cshubhraj > yoti.datta%40amd.com%7C651e141296fb497b6c2e08dacedb65ad%7C3dd896 > 1fe4884e608e11a82d994e183d%7C0%7C0%7C638049738949855658%7CUnkn > own%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik > 1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=ny08zTdgJKxXC > dwYaCWFS3mwd65LDqFAIYfjao6gO8Y%3D&reserved=0 > --- > drivers/i2c/busses/i2c-cadence.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c- > cadence.c > index fe0cd205502d..40d0cc6bb996 100644 > --- a/drivers/i2c/busses/i2c-cadence.c > +++ b/drivers/i2c/busses/i2c-cadence.c > @@ -852,7 +852,8 @@ static int cdns_i2c_master_xfer(struct i2c_adapter > *adap, struct i2c_msg *msgs, > CDNS_I2C_POLL_US, CDNS_I2C_TIMEOUT_US); > if (ret) { > ret = -EAGAIN; > - i2c_recover_bus(adap); > + if (id->adap.bus_recovery_info) > + i2c_recover_bus(adap); > goto out; > } > > @@ -1262,10 +1263,10 @@ static int cdns_i2c_probe(struct platform_device > *pdev) > } > > id->rinfo.pinctrl = devm_pinctrl_get(&pdev->dev); > - if (IS_ERR(id->rinfo.pinctrl)) { > + if (IS_ERR(id->rinfo.pinctrl)) > dev_info(&pdev->dev, "can't get pinctrl, bus recovery not > supported\n"); > - return PTR_ERR(id->rinfo.pinctrl); > - } > + else > + id->adap.bus_recovery_info = &id->rinfo; May be we could differentiate between ENODEV and other errors. As we want to do this for the case when it is not provided. > > id->membase = devm_platform_get_and_ioremap_resource(pdev, 0, > &r_mem); > if (IS_ERR(id->membase)) > @@ -1283,7 +1284,6 @@ static int cdns_i2c_probe(struct platform_device > *pdev) > id->adap.retries = 3; /* Default retry value. */ > id->adap.algo_data = id; > id->adap.dev.parent = &pdev->dev; > - id->adap.bus_recovery_info = &id->rinfo; > init_completion(&id->xfer_done); > snprintf(id->adap.name, sizeof(id->adap.name), > "Cadence I2C at %08lx", (unsigned long)r_mem->start); > -- > 2.32.0