[RFC] ALSA: hda: Add workaround to adapt to Loongson 7A1000 controller

[Kaige Li]

On 07/31/2020 02:29 PM, Takashi Iwai wrote:

> On Fri, 31 Jul 2020 04:41:54 +0200,
> Kaige Li wrote:
>> There's some issues that cause palyback without a sound on Loongson
>> platform (3A3000 + 7A1000) with a Realtek ALC269 codec. After lengthy
>> debugging sessions, we solved it by adding workaround.
>>
>> Signed-off-by: Kaige Li <likaige at loongson.cn>
> Thanks for the patch.  But this can't be taken as is due to the design
> problem.  Namely...
>
>> --- a/sound/hda/hdac_controller.c
>> +++ b/sound/hda/hdac_controller.c
>> @@ -9,6 +9,7 @@
>>   #include <sound/core.h>
>>   #include <sound/hdaudio.h>
>>   #include <sound/hda_register.h>
>> +#include "../pci/hda/hda_controller.h"
> ... here already suspicious, and ...
>
>>   #include "local.h"
>>   
>>   /* clear CORB read pointer properly */
>> @@ -42,6 +43,8 @@ static void azx_clear_corbrp(struct hdac_bus *bus)
>>    */
>>   void snd_hdac_bus_init_cmd_io(struct hdac_bus *bus)
>>   {
>> +	struct azx *chip = bus_to_azx(bus);
> ... here you cast the hdac_bus object to its child class.  This is
> disallowed, as it's a layer violation and would break if another child
> class like ASoC driver is used with this patch.
>
> IOW, inside the code in sound/hda/*, you must not use the contents in
> sound/pci/hda/* and include/sound/hda_codec.h.
>
> If any new workaround is needed, introduce a new flag in struct
> hdac_bus.

Thank you for your reply and suggestions. I will review it, and see how 
hdac_bus works.

Thanks,
Kaige
> thanks,
>
> Takashi