linux-kernel - Re: [PATCH] spi: dw: Fix spi registration for controllers overriding CS

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Message-ID: <20201125123935.akerf6mlgiwdemmm@mobilestation>
Date:   Wed, 25 Nov 2020 15:39:35 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Lars Povlsen <lars.povlsen@...rochip.com>
Cc:     Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: dw: Fix spi registration for controllers overriding
 CS

Hello Lars

On Fri, Nov 20, 2020 at 10:34:14PM +0100, Lars Povlsen wrote:
> When SPI DW memory ops support was introduced, there was a check for
> excluding controllers which supplied their own CS function. Even so,
> the mem_ops pointer is *always* presented to the SPI core.
> 
> This causes the SPI core sanity check in spi_controller_check_ops() to
> refuse registration, since a mem_ops pointer is being supplied without
> an exec_op member function.
> 
> The end result is failure of the SPI DW driver on sparx5 and similar
> platforms.
> 
> The fix in the core SPI DW driver is to avoid presenting the mem_ops
> pointer if the exec_op function is not set.

Thanks for sending the patch fixing the regression.
Acked-by: Serge Semin <fancer.lancer@...il.com>

> 
> Fixes: 6423207e57ea (spi: dw: Add memory operations support)
> Signed-off-by: Lars Povlsen <lars.povlsen@...rochip.com>
> ---
>  drivers/spi/spi-dw-core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index 2e50cc0a9291..a0794eac2094 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -875,7 +875,8 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
>  		master->set_cs = dw_spi_set_cs;
>  	master->transfer_one = dw_spi_transfer_one;
>  	master->handle_err = dw_spi_handle_err;
> -	master->mem_ops = &dws->mem_ops;
> +	if (dws->mem_ops.exec_op)
> +		master->mem_ops = &dws->mem_ops;
>  	master->max_speed_hz = dws->max_freq;
>  	master->dev.of_node = dev->of_node;
>  	master->dev.fwnode = dev->fwnode;
> --
> 2.25.1