Re: [PATCH v3 2/6] ALSA: hda/tegra: Reset hardware

Takashi Iwai
2021-01-26T07:50:31Z

On Wed, 20 Jan 2021 01:31:50 +0100,
Dmitry Osipenko wrote:
>
> Reset hardware on RPM-resume in order to bring it into a predictable
> state.
>
> Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30 audio works
> Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30 boot-tested
> Tested-by: Nicolas Chauvet <kwizart@gmail.com> # TK1 boot-tested
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>

Currently we have neither dependency nor reverse-selection of
CONFIG_RESET_CONTROLLER. It wouldn't be a problem for builds, but
you'll get a runtime error from
devm_reset_control_array_get_exclusive() always when
CONFIG_RESET_CONTROLLER=n.

I guess it must be a corner case, but just to be sure.

thanks,

Takashi

> ---
> sound/pci/hda/hda_tegra.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/sound/pci/hda/hda_tegra.c b/sound/pci/hda/hda_tegra.c
> index a25bf7083c28..04dcd4cdfd9e 100644
> --- a/sound/pci/hda/hda_tegra.c
> +++ b/sound/pci/hda/hda_tegra.c
> @@ -17,6 +17,7 @@
> #include <linux/moduleparam.h>
> #include <linux/mutex.h>
> #include <linux/of_device.h>
> +#include <linux/reset.h>
> #include <linux/slab.h>
> #include <linux/time.h>
> #include <linux/string.h>
> @@ -70,6 +71,7 @@
> struct hda_tegra {
> struct azx chip;
> struct device *dev;
> + struct reset_control *reset;
> struct clk_bulk_data clocks[3];
> unsigned int nclocks;
> void __iomem *regs;
> @@ -167,6 +169,12 @@ static int __maybe_unused hda_tegra_runtime_resume(struct device *dev)
> struct hda_tegra *hda = container_of(chip, struct hda_tegra, chip);
> int rc;
>
> + if (!chip->running) {
> + rc = reset_control_assert(hda->reset);
> + if (rc)
> + return rc;
> + }
> +
> rc = clk_bulk_prepare_enable(hda->nclocks, hda->clocks);
> if (rc != 0)
> return rc;
> @@ -176,6 +184,12 @@ static int __maybe_unused hda_tegra_runtime_resume(struct device *dev)
> /* disable controller wake up event*/
> azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) &
> ~STATESTS_INT_MASK);
> + } else {
> + usleep_range(10, 100);
> +
> + rc = reset_control_deassert(hda->reset);
> + if (rc)
> + return rc;
> }
>
> return 0;
> @@ -441,6 +455,12 @@ static int hda_tegra_probe(struct platform_device *pdev)
> return err;
> }
>
> + hda->reset = devm_reset_control_array_get_exclusive(&pdev->dev);
> + if (IS_ERR(hda->reset)) {
> + err = PTR_ERR(hda->reset);
> + goto out_free;
> + }
> +
> hda->clocks[hda->nclocks++].id = "hda";
> hda->clocks[hda->nclocks++].id = "hda2hdmi";
> hda->clocks[hda->nclocks++].id = "hda2codec_2x";
> --
> 2.29.2
>