Re: [PATCH v2 01/13] drm/mediatek: add refcount for DPI power on/off

CK Hu
2018-09-05T09:30:49Z

Hi, Bibby:

This looks reasonable, but why MT8173 doesn't need this patch? So
describe more about why MT7623 need this patch. If this is caused by
latest DRM core flow change, I think we should treat this patch
independent with MT7623.

Regards,
CK

On Wed, 2018-09-05 at 16:31 +0800, Bibby Hsieh wrote:
> From: chunhui dai <chunhui.dai@mediatek.com>
>
> add refcount for DPI power on/off to protect the flow
>
> Signed-off-by: chunhui dai <chunhui.dai@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_dpi.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 6c0ea39d5739..d9373e67d328 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -77,6 +77,7 @@ struct mtk_dpi {
> enum mtk_dpi_out_bit_num bit_num;
> enum mtk_dpi_out_channel_swap channel_swap;
> bool power_sta;
> + int refcount;
> u8 power_ctl;
> };
>
> @@ -369,6 +370,12 @@ static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>
> static void mtk_dpi_power_off(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
> {
> + if (WARN_ON(dpi->refcount == 0))
> + return;
> +
> + if (--dpi->refcount != 0)
> + return;
> +
> dpi->power_ctl &= ~pctl;
>
> if ((dpi->power_ctl & DPI_POWER_START) ||
> @@ -388,14 +395,17 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
> {
> int ret;
>
> + if (++dpi->refcount != 1)
> + return 0;
> +
> dpi->power_ctl |= pctl;
>
> if (!(dpi->power_ctl & DPI_POWER_START) &&
> !(dpi->power_ctl & DPI_POWER_ENABLE))
> - return 0;
> + goto err_refcount;
>
> if (dpi->power_sta)
> - return 0;
> + goto err_refcount;
>
> ret = clk_prepare_enable(dpi->engine_clk);
> if (ret) {
> @@ -417,6 +427,8 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
> clk_disable_unprepare(dpi->engine_clk);
> err_eng:
> dpi->power_ctl &= ~pctl;
> +err_refcount:
> + dpi->refcount--;
> return ret;
> }
>