Re: [PATCH v2 1/4] i2c: imx: only poll for bus busy in multi master mode

[Stefan Eichenberger]

Hi Fabio,

On Thu, Aug 22, 2024 at 08:07:44AM -0300, Fabio Estevam wrote:
> Hi Stefan and Oleksij,
> 
> On Wed, Aug 21, 2024 at 8:01 AM Fabio Estevam <festevam@xxxxxxxxx> wrote:
> 
> > This fixes a pca953x probe error on an imx8mp board running linux-stable 6.6:
> >
> > [    1.893260] pca953x 2-0020: failed writing register
> > [    1.898258] pca953x 2-0020: probe with driver pca953x failed with error -11
> >
> > Could you please add a Fixes tag and Cc stable so that this can reach
> > the stable kernels?
> >
> > Tested-by: Fabio Estevam <festevam@xxxxxxx>
> 
> I am sorry, but I have to withdraw my Tested-by tag.
> 
> For debugging purposes, I kept 'fw_devlink=off' in the kernel command
> line and that's what made it work.
> 
> Removing 'fw_devlink=off' I still get the probe failure, even with all
> the series from Stefan applied:
> 
> [    1.849097] pca953x 2-0020: supply vcc not found, using dummy regulator
> [    1.855857] pca953x 2-0020: using no AI
> [    1.859965] i2c i2c-2: <i2c_imx_write> write failed with -6
> [    1.865578] pca953x 2-0020: failed writing register: -6
> 
> In my case, I can get the pca953x driver to probe successfully in one
> of the following cases:
> 
> 1. Select pca953x as a module instead of built-in
> 
> or
> 
> 2. Pass 'fw_devlink=off' in the kernel command line
> 
> or
> 
> 3.  Register the i2c-imx driver as module_platform_driver():
> 
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1586,17 +1586,7 @@ static struct platform_driver i2c_imx_driver = {
>         .id_table = imx_i2c_devtype,
>  };
> 
> -static int __init i2c_adap_imx_init(void)
> -{
> -       return platform_driver_register(&i2c_imx_driver);
> -}
> -subsys_initcall(i2c_adap_imx_init);
> -
> -static void __exit i2c_adap_imx_exit(void)
> -{
> -       platform_driver_unregister(&i2c_imx_driver);
> -}
> -module_exit(i2c_adap_imx_exit);
> +module_platform_driver(i2c_imx_driver);
> 
> or
> 
> 4. Use the NXP vendor kernel imx_6.1.22_2.0.0 kernel
> 
> Stefan, do you get the arbitration errors if you try methods 2 or 3 above?

I have tried method 3 an it did not work for me. I still have the same
issue as before that sometimes the timeout occurs and the ads1015 will
not ack anymore. So the patch series is still the only way I found so
far to get rid of the problem. I also checked the datasheet of a pca953x
device (PCAL6416A) and it doesn't seem to have a timeout mechanism.
Therefore, I don't think we are affected by the same issue.

Regards,
Stefan