[AMD Official Use Only - General]
Hi ,
Thanks for the patch
> -----Original Message-----
> From: carsten.haitzler@xxxxxxxxxxxx <carsten.haitzler@xxxxxxxxxxxx>
> Sent: Friday, November 25, 2022 5:21 PM
> To: michal.simek@xxxxxxxxxx; shubhrajyoti.datta@xxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
> Subject: [PATCH] i2c: cadence: Fix regression with bus recovery
>
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>
> From: Carsten Haitzler <carsten.haitzler@xxxxxxx>
>
> 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 <carsten.haitzler@xxxxxxx>
> ---
> 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
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