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SubjectRe: [PATCH] ASoC: stm32: sai: Use of_device_get_match_data() to simplify code
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Hello Tang,

Thanks for the patch. Unfortunately this patch introduces a regression.

In the SAI driver of_device_id struct the data is a simple enum cast to
void* pointer.
static const struct of_device_id stm32_sai_sub_ids[] = {
.data = (void *)STM_SAI_A_ID},

This data is an ID which can be set to 0x0.
Here we have no way to know to discriminate between an error returned by
of_device_get_match_data() or a data id set to 0x0.

The current patch requires a change in the driver.
Either changing STM_SAI_x_ID enums, or replacing data by a struct.
For instance:
struct stm32_sai_comp_data {
unsigned int id;
}
struct stm32_sai_comp_data stm32_sai_comp_data_a = {
.id = STM_SAI_A_ID;
}
struct of_device_id stm32_sai_sub_ids[] = {
.data = &stm32_sai_comp_data_a},
}

Regards
Olivier

On 5/19/22 14:42, Tang Bin wrote:
> Retrieve of match data, it's better and cleaner to use
> 'of_device_get_match_data' over 'of_match_device'.
>
> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
> ---
> sound/soc/stm/stm32_sai_sub.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/sound/soc/stm/stm32_sai_sub.c b/sound/soc/stm/stm32_sai_sub.c
> index dd636af81..d300605a2 100644
> --- a/sound/soc/stm/stm32_sai_sub.c
> +++ b/sound/soc/stm/stm32_sai_sub.c
> @@ -1500,7 +1500,6 @@ static int stm32_sai_sub_parse_of(struct platform_device *pdev,
> static int stm32_sai_sub_probe(struct platform_device *pdev)
> {
> struct stm32_sai_sub_data *sai;
> - const struct of_device_id *of_id;
> const struct snd_dmaengine_pcm_config *conf = &stm32_sai_pcm_config;
> int ret;
>
> @@ -1508,10 +1507,9 @@ static int stm32_sai_sub_probe(struct platform_device *pdev)
> if (!sai)
> return -ENOMEM;
>
> - of_id = of_match_device(stm32_sai_sub_ids, &pdev->dev);
> - if (!of_id)
> + sai->id = (uintptr_t)of_device_get_match_data(&pdev->dev);
> + if (!sai->id)
> return -EINVAL;
> - sai->id = (uintptr_t)of_id->data;
>
> sai->pdev = pdev;
> mutex_init(&sai->ctrl_lock);

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