Re: [RFC PATCH 3/3] drm: bridge: samsung-dsim: Remove init quirk for Exynos

[Marek Szyprowski]

On 18.04.2023 12:42, Frieder Schrempf wrote:
> From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
>
> Assuming that with the init flow fixed to meet the documentation at
> [1] and the pre_enable_prev_first flag set in downstream bridge/panel
> drivers which require it, we can use the default flow for Exynos as
> already done for i.MX8M.
>
> [1] https://docs.kernel.org/gpu/drm-kms-helpers.html#mipi-dsi-bridge-operation
>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> ---
> I have no idea if my assumptions are correct and if this works at all.
> There's a very good chance it doesn't...

Unfortunately this change breaks all Exynos boards with DSI panels. I've 
check all 4 panels that are in mainline and none worked.

> ---
>   drivers/gpu/drm/bridge/samsung-dsim.c | 39 ++++++++-------------------
>   1 file changed, 11 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index 9775779721d9..8c68b767ae50 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1336,18 +1336,12 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge,
>   
>   	dsi->state |= DSIM_STATE_ENABLED;
>   
> -	/*
> -	 * For Exynos-DSIM the downstream bridge, or panel are expecting
> -	 * the host initialization during DSI transfer.
> -	 */
> -	if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) {
> -		ret = samsung_dsim_init(dsi);
> -		if (ret)
> -			return;
> +	ret = samsung_dsim_init(dsi);
> +	if (ret)
> +		return;
>   
> -		samsung_dsim_set_display_mode(dsi);
> -		samsung_dsim_set_display_enable(dsi, true);
> -	}
> +	samsung_dsim_set_display_mode(dsi);
> +	samsung_dsim_set_display_enable(dsi, true);
>   }
>   
>   static void samsung_dsim_atomic_enable(struct drm_bridge *bridge,
> @@ -1356,14 +1350,9 @@ static void samsung_dsim_atomic_enable(struct drm_bridge *bridge,
>   	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
>   	u32 reg;
>   
> -	if (samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) {
> -		samsung_dsim_set_display_mode(dsi);
> -		samsung_dsim_set_display_enable(dsi, true);
> -	} else {
> -		reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> -		reg &= ~DSIM_FORCE_STOP_STATE;
> -		samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
> -	}
> +	reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> +	reg &= ~DSIM_FORCE_STOP_STATE;
> +	samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
>   
>   	dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
>   }
> @@ -1377,11 +1366,9 @@ static void samsung_dsim_atomic_disable(struct drm_bridge *bridge,
>   	if (!(dsi->state & DSIM_STATE_ENABLED))
>   		return;
>   
> -	if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) {
> -		reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> -		reg |= DSIM_FORCE_STOP_STATE;
> -		samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
> -	}
> +	reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> +	reg |= DSIM_FORCE_STOP_STATE;
> +	samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
>   
>   	dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE;
>   }
> @@ -1680,10 +1667,6 @@ static ssize_t samsung_dsim_host_transfer(struct mipi_dsi_host *host,
>   	if (!(dsi->state & DSIM_STATE_ENABLED))
>   		return -EINVAL;
>   
> -	ret = samsung_dsim_init(dsi);
> -	if (ret)
> -		return ret;
> -
>   	ret = mipi_dsi_create_packet(&xfer.packet, msg);
>   	if (ret < 0)
>   		return ret;

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland