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

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Message-ID: <CAOMZO5CeT+LvQ__3GUf6teL3=8pZe5qxmFffYJX-h3E27UXwtQ@mail.gmail.com>
Date: Thu, 22 Aug 2024 08:07:44 -0300
From: Fabio Estevam <festevam@...il.com>
To: Stefan Eichenberger <eichest@...il.com>
Cc: o.rempel@...gutronix.de, kernel@...gutronix.de, andi.shyti@...nel.org, 
	shawnguo@...nel.org, s.hauer@...gutronix.de, Frank.Li@....com, 
	francesco.dolcini@...adex.com, linux-i2c@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Stefan Eichenberger <stefan.eichenberger@...adex.com>
Subject: Re: [PATCH v2 1/4] i2c: imx: only poll for bus busy in multi master mode

Hi Stefan and Oleksij,

On Wed, Aug 21, 2024 at 8:01 AM Fabio Estevam <festevam@...il.com> 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@...x.de>

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?