Re: [PATCH v1 10/11] ALSA: hda: cs35l41: Add device_link between HDA and cs35l41_hda

Takashi Iwai
2023-07-20T14:21:41Z

On Thu, 20 Jul 2023 15:31:46 +0200,
Stefan Binding wrote:
>
> To ensure consistency between the HDA core and the CS35L41 HDA
> driver, add a device_link between them. This ensures that the
> HDA core will suspend first, and resume second, meaning the
> amp driver will not miss any events from the playback hook from
> the HDA core during system suspend and resume.
>
> Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
> ---
> sound/pci/hda/cs35l41_hda.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/sound/pci/hda/cs35l41_hda.c b/sound/pci/hda/cs35l41_hda.c
> index 70aa819cfbd64..175378cdf9dfa 100644
> --- a/sound/pci/hda/cs35l41_hda.c
> +++ b/sound/pci/hda/cs35l41_hda.c
> @@ -1063,6 +1063,7 @@ static int cs35l41_hda_bind(struct device *dev, struct device *master, void *mas
> {
> struct cs35l41_hda *cs35l41 = dev_get_drvdata(dev);
> struct hda_component *comps = master_data;
> + unsigned int sleep_flags;
> int ret = 0;
>
> if (!comps || cs35l41->index < 0 || cs35l41->index >= HDA_MAX_COMPONENTS)
> @@ -1102,6 +1103,11 @@ static int cs35l41_hda_bind(struct device *dev, struct device *master, void *mas
>
> mutex_unlock(&cs35l41->fw_mutex);
>
> + sleep_flags = lock_system_sleep();
> + if (!device_link_add(&comps->codec->core.dev, cs35l41->dev, DL_FLAG_STATELESS))
> + dev_warn(dev, "Unable to create device link\n");
> + unlock_system_sleep(sleep_flags);

Is lock_system_sleep() mandatory for device_link_add()? The function
takes its rw lock for the race, I suppose.

thanks,

Takashi