[alsa-devel] [PATCH 2/2] vgaswitchreoo: set audio client id in vgaswitchreoo enable function

[jimqu]

在 2018/7/13 16:46, Takashi Iwai 写道:
> On Fri, 13 Jul 2018 10:06:02 +0200,
> Jim Qu wrote:
>> On modern laptop, there are more and more platforms
>> have two GPUs, and each of them maybe have audio codec
>> for HDMP/DP output. For some dGPU which is no output,
>> audio codec usually is disabled.
>>
>> In currect HDA audio driver, it will set all codec as
>> VGA_SWITCHEROO_DIS, the audio which is binded to UMA
>> will be suspended if user use debugfs to contorl power
>>
>> In HDA driver side, it is difficult to know which GPU
>> the audio has binded to. So set the bound gpu pci dev
>> to vgaswitchroo, the correct audio id will be set in
>> vgaswitchreoo enable function.
>>
>> Signed-off-by: Jim Qu <Jim.Qu at amd.com>
> The idea looks good to me.  Just a nitpick:
>
>> @@ -1319,15 +1319,16 @@ static const struct vga_switcheroo_client_ops azx_vs_ops = {
>>   static int register_vga_switcheroo(struct azx *chip)
>>   {
>>   	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
>> +	struct pci_dev * p;
>>   	int err;
>>   
>>   	if (!hda->use_vga_switcheroo)
>>   		return 0;
>> -	/* FIXME: currently only handling DIS controller
>> -	 * is there any machine with two switchable HDMI audio controllers?
>> -	 */
>> -	err = vga_switcheroo_register_audio_client(chip->pci, &azx_vs_ops,
>> -						   VGA_SWITCHEROO_DIS);
>> +
>> +	p  = get_bound_vga(chip->pci);
>> +	err = vga_switcheroo_register_audio_client(chip->pci, &azx_vs_ops, p);
>> +	if (p)
>> +		pci_dev_put(p);
> Passing a NULL vga_dev won't work, so the NULL check after calling
> vga_switcheroo_register_audio_client() is moot.  If any, it should be
> checked before that.
>

  The hda->use_vga_switcheroo is set to 1 in init_vga_switcheroo() if 
bound vga pci dev is not NULL. Since the hda->use_vga_switcheroo is 
checked at beginning of the function. so the p which pass into 
vga_switcheroo_register_audio_client() is constant valid value.

Thanks
JimQu
> thanks,
>
> Takashi