Re: [PATCH 3/4] ALSA: hda: Workaround for SDnCTL register on loongson controller

[Takashi Iwai <tiwai@suse.de>]

On Wed, 31 May 2023 05:21:33 +0200,
Yanteng Si wrote:
> 
> On loongson controller, after calling snd_hdac_stream_updateb()
> to enable DMA engine, the SDnCTL.STRM will become to zero.  We
> need to access SDnCTL in dword to keep SDnCTL.STRM is not changed.
> 
> Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
> Signed-off-by: Yingkun Meng <mengyingkun@loongson.cn>
> ---
>  sound/hda/hdac_stream.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
> index 1f56fd33b9af..90fbf9fea2b3 100644
> --- a/sound/hda/hdac_stream.c
> +++ b/sound/hda/hdac_stream.c
> @@ -13,6 +13,7 @@
>  #include <sound/hdaudio.h>
>  #include <sound/hda_register.h>
>  #include "trace.h"
> +#include "../pci/hda/hda_controller.h"
>  
>  /*
>   * the hdac_stream library is intended to be used with the following
> @@ -130,6 +131,7 @@ EXPORT_SYMBOL_GPL(snd_hdac_stream_init);
>  void snd_hdac_stream_start(struct hdac_stream *azx_dev)
>  {
>  	struct hdac_bus *bus = azx_dev->bus;
> +	struct azx *chip = bus_to_azx(bus);
>  	int stripe_ctl;
>  
>  	trace_snd_hdac_stream_start(bus, azx_dev);
> @@ -150,7 +152,11 @@ void snd_hdac_stream_start(struct hdac_stream *azx_dev)
>  					stripe_ctl);
>  	}
>  	/* set DMA start and interrupt mask */
> -	snd_hdac_stream_updateb(azx_dev, SD_CTL,
> +	if (chip->driver_caps & AZX_DCAPS_LOONGSON_WORKAROUND)
> +		snd_hdac_stream_updatel(azx_dev, SD_CTL,
> +				0, SD_CTL_DMA_START | SD_INT_MASK);
> +	else
> +		snd_hdac_stream_updateb(azx_dev, SD_CTL,
>  				0, SD_CTL_DMA_START | SD_INT_MASK);

Similarly like the patch 2, this has to be handled with a new flag
added to struct hdac_bus.


Takashi