[PATCH v2 05/12] drm: bridge: samsung-dsim: Add DSI init in bridge pre_enable()

[Marek Szyprowski]

On 04.05.2022 13:40, Jagan Teki wrote:
> Host transfer() in DSI master will invoke only when the DSI commands
> are sent from DSI devices like DSI Panel or DSI bridges and this
> host transfer wouldn't invoke for I2C-based-DSI bridge drivers.
>
> Handling DSI host initialization in transfer calls misses the
> controller setup for I2C configured DSI bridges.
>
> This patch adds the DSI initialization from transfer to bridge
> pre_enable as the bridge pre_enable API is invoked by core as
> it is common across all classes of DSI device drivers.
>
> v2:
> * check initialized state in samsung_dsim_init
>
> v1:
> * keep DSI init in host transfer
>
> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>

This doesn't work with Exynos DSI and DSI panels. Here is a bit more 
detailed explanation and my solution for this:

https://lore.kernel.org/all/e96197f9-948a-997e-5453-9f9d179b5f5a@samsung.com/


> ---
>   drivers/gpu/drm/bridge/samsung-dsim.c | 18 ++++++++++++------
>   1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index 60dc863113a0..b9361af5ef2d 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1259,6 +1259,9 @@ static int samsung_dsim_init(struct samsung_dsim *dsi)
>   {
>   	const struct samsung_dsim_driver_data *driver_data = dsi->driver_data;
>   
> +	if (dsi->state & DSIM_STATE_INITIALIZED)
> +		return 0;
> +
>   	samsung_dsim_reset(dsi);
>   	samsung_dsim_enable_irq(dsi);
>   
> @@ -1271,6 +1274,8 @@ static int samsung_dsim_init(struct samsung_dsim *dsi)
>   	samsung_dsim_set_phy_ctrl(dsi);
>   	samsung_dsim_init_link(dsi);
>   
> +	dsi->state |= DSIM_STATE_INITIALIZED;
> +
>   	return 0;
>   }
>   
> @@ -1290,6 +1295,10 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge,
>   	}
>   
>   	dsi->state |= DSIM_STATE_ENABLED;
> +
> +	ret = samsung_dsim_init(dsi);
> +	if (ret)
> +		return;
>   }
>   
>   static void samsung_dsim_atomic_enable(struct drm_bridge *bridge,
> @@ -1464,12 +1473,9 @@ static ssize_t samsung_dsim_host_transfer(struct mipi_dsi_host *host,
>   	if (!(dsi->state & DSIM_STATE_ENABLED))
>   		return -EINVAL;
>   
> -	if (!(dsi->state & DSIM_STATE_INITIALIZED)) {
> -		ret = samsung_dsim_init(dsi);
> -		if (ret)
> -			return ret;
> -		dsi->state |= DSIM_STATE_INITIALIZED;
> -	}
> +	ret = samsung_dsim_init(dsi);
> +	if (ret)
> +		return ret;
>   
>   	ret = mipi_dsi_create_packet(&xfer.packet, msg);
>   	if (ret < 0)

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