Re: [PATCH 1/2] drm/bridge: dw-hdmi: Move vmalloc PCM buffer management into the driver

[Neil Armstrong <neil.armstrong@linaro.org>]

On 07/08/2024 17:27, Takashi Iwai wrote:
> The dw-hdmi drm bridge driver is the only one who still uses the ALSA
> vmalloc helper API functions.  A previous attempt to change the way of
> buffer management wasn't taken for this legacy stuff, as we had little
> chance for test and some risk of major breaking.
> Instead, this patch moves the vmalloc buffer stuff into the dw-hdmi
> driver code itself, so that we can drop them from ALSA core code
> afterwards.
> 
> There should be no functional changes.
> 
> Link: https://lore.kernel.org/20191210154536.29819-1-tiwai@suse.de
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
>   .../drm/bridge/synopsys/dw-hdmi-ahb-audio.c   | 30 ++++++++++++++++---
>   1 file changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-ahb-audio.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-ahb-audio.c
> index 67b8d17a722a..221e9a4edb40 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-ahb-audio.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-ahb-audio.c
> @@ -8,6 +8,7 @@
>   #include <linux/interrupt.h>
>   #include <linux/module.h>
>   #include <linux/platform_device.h>
> +#include <linux/vmalloc.h>
>   #include <drm/bridge/dw_hdmi.h>
>   #include <drm/drm_edid.h>
>   
> @@ -388,15 +389,36 @@ static int dw_hdmi_close(struct snd_pcm_substream *substream)
>   
>   static int dw_hdmi_hw_free(struct snd_pcm_substream *substream)
>   {
> -	return snd_pcm_lib_free_vmalloc_buffer(substream);
> +	struct snd_pcm_runtime *runtime = substream->runtime;
> +
> +	vfree(runtime->dma_area);
> +	runtime->dma_area = NULL;
> +	return 0;
>   }
>   
>   static int dw_hdmi_hw_params(struct snd_pcm_substream *substream,
>   	struct snd_pcm_hw_params *params)
>   {
> +	struct snd_pcm_runtime *runtime = substream->runtime;
> +	size_t size = params_buffer_bytes(params);
> +
>   	/* Allocate the PCM runtime buffer, which is exposed to userspace. */
> -	return snd_pcm_lib_alloc_vmalloc_buffer(substream,
> -						params_buffer_bytes(params));
> +	if (runtime->dma_area) {
> +		if (runtime->dma_bytes >= size)
> +			return 0; /* already large enough */
> +		vfree(runtime->dma_area);
> +	}
> +	runtime->dma_area = vzalloc(size);
> +	if (!runtime->dma_area)
> +		return -ENOMEM;
> +	runtime->dma_bytes = size;
> +	return 1;
> +}
> +
> +static struct page *dw_hdmi_get_page(struct snd_pcm_substream *substream,
> +				     unsigned long offset)
> +{
> +	return vmalloc_to_page(substream->runtime->dma_area + offset);
>   }
>   
>   static int dw_hdmi_prepare(struct snd_pcm_substream *substream)
> @@ -515,7 +537,7 @@ static const struct snd_pcm_ops snd_dw_hdmi_ops = {
>   	.prepare = dw_hdmi_prepare,
>   	.trigger = dw_hdmi_trigger,
>   	.pointer = dw_hdmi_pointer,
> -	.page = snd_pcm_lib_get_vmalloc_page,
> +	.page = dw_hdmi_get_page,
>   };
>   
>   static int snd_dw_hdmi_probe(struct platform_device *pdev)

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>