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    SubjectRe: [PATCH v2 2/6] ASoC: amd: yc: Add a module parameter to influence pdm_gain
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    On 30. 01. 23 23:07, Mario Limonciello wrote:
    > In case of regressions for any users that the new pdm_gain value is
    > too high and for additional debugging, introduce a module parameter
    > that would let them configure it.
    >
    > This parameter should be removed in the future:
    > * If it's determined that the parameter is not needed, just hardcode
    > the correct value as before
    > * If users do end up using it to debug and report different values
    > we should introduce a config knob that can have policy set by ucm.
    >
    > Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
    > ---
    > v1->v2:
    > * Add a guard for values > 3 to overflow the FIELD_PREP
    > * Clear ACP_WOV_GAIN_CONTROL before setting it
    > ---
    > sound/soc/amd/yc/acp6x-pdm-dma.c | 10 +++++++++-
    > sound/soc/amd/yc/acp6x.h | 2 +-
    > 2 files changed, 10 insertions(+), 2 deletions(-)
    >
    > diff --git a/sound/soc/amd/yc/acp6x-pdm-dma.c b/sound/soc/amd/yc/acp6x-pdm-dma.c
    > index acecd6a4ec4b1..2bb3ea14bae9c 100644
    > --- a/sound/soc/amd/yc/acp6x-pdm-dma.c
    > +++ b/sound/soc/amd/yc/acp6x-pdm-dma.c
    > @@ -7,6 +7,7 @@
    >
    > #include <linux/platform_device.h>
    > #include <linux/module.h>
    > +#include <linux/bitfield.h>
    > #include <linux/err.h>
    > #include <linux/io.h>
    > #include <sound/pcm_params.h>
    > @@ -18,6 +19,10 @@
    >
    > #define DRV_NAME "acp_yc_pdm_dma"
    >
    > +static int pdm_gain = 3;
    > +module_param(pdm_gain, int, 0644);
    > +MODULE_PARM_DESC(pdm_gain, "Gain control (0-3)");
    > +
    > static const struct snd_pcm_hardware acp6x_pdm_hardware_capture = {
    > .info = SNDRV_PCM_INFO_INTERLEAVED |
    > SNDRV_PCM_INFO_BLOCK_TRANSFER |
    > @@ -55,7 +60,10 @@ static void acp6x_enable_pdm_clock(void __iomem *acp_base)
    >
    > acp6x_writel(pdm_clk_enable, acp_base + ACP_WOV_CLK_CTRL);
    > pdm_ctrl = acp6x_readl(acp_base + ACP_WOV_MISC_CTRL);
    > - pdm_ctrl |= ACP_WOV_MISC_CTRL_MASK;
    > + pdm_ctrl &= FIELD_PREP(ACP_WOV_GAIN_CONTROL, 0);

    It should be 'pdm_ctrl &= ~ACP_WOV_GAIN_CONTROL' see include/linux/bitfield.h
    (Modify: comment).

    > + if (pdm_gain > 3)
    > + pdm_gain = 3;

    Negative values are not handled. Use clamp(pdm_gain, 0, 3) - see
    include/linux/minmax.h.

    > + pdm_ctrl |= FIELD_PREP(ACP_WOV_GAIN_CONTROL, pdm_gain);
    > acp6x_writel(pdm_ctrl, acp_base + ACP_WOV_MISC_CTRL);

    Jaroslav

    --
    Jaroslav Kysela <perex@perex.cz>
    Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

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