[PATCH] drm/mediatek: allow commands to be sent during video mode

[CK Hu]

Hi, Julien:

On Mon, 2022-01-24 at 16:22 +0100, Julien STEPHAN wrote:
> When the DSI is in video mode, all commands are rejected.
> 
> Detect current DSI mode in mtk_dsi_host_transfer() and switch modes
> temporarily to allow commands to be sent.

Is this patch a bug-fix or new feature? If this is a bug-fix, add Fixes
tag [1] in this patch. If this is a new feature, describe more about
more about this feature, such as support more panel or something.

[1] 
https://www.kernel.org/doc/html/v5.16/process/submitting-patches.html

Regards,
CK

> 
> Signed-off-by: Julien STEPHAN <jstephan at baylibre.com>
> Signed-off-by: Mattijs Korpershoek <mkorpershoek at baylibre.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 34 ++++++++++++++++++++++----
> ----
>  1 file changed, 25 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 5d90d2eb0019..7d66fdc7f81d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -891,24 +891,34 @@ static ssize_t mtk_dsi_host_transfer(struct
> mipi_dsi_host *host,
>  	u8 read_data[16];
>  	void *src_addr;
>  	u8 irq_flag = CMD_DONE_INT_FLAG;
> -
> -	if (readl(dsi->regs + DSI_MODE_CTRL) & MODE) {
> -		DRM_ERROR("dsi engine is not command mode\n");
> -		return -EINVAL;
> +	u32 dsi_mode;
> +
> +	dsi_mode = readl(dsi->regs + DSI_MODE_CTRL);
> +	if (dsi_mode & MODE) {
> +		mtk_dsi_stop(dsi);
> +		if (mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG,
> 500)) {
> +			recv_cnt = -EINVAL;
> +			goto restore_dsi_mode;
> +		}
>  	}
>  
>  	if (MTK_DSI_HOST_IS_READ(msg->type))
>  		irq_flag |= LPRX_RD_RDY_INT_FLAG;
>  
> -	if (mtk_dsi_host_send_cmd(dsi, msg, irq_flag) < 0)
> -		return -ETIME;
> +	if (mtk_dsi_host_send_cmd(dsi, msg, irq_flag) < 0) {
> +		recv_cnt = -ETIME;
> +		goto restore_dsi_mode;
> +	}
>  
> -	if (!MTK_DSI_HOST_IS_READ(msg->type))
> -		return 0;
> +	if (!MTK_DSI_HOST_IS_READ(msg->type)) {
> +		recv_cnt = 0;
> +		goto restore_dsi_mode;
> +	}
>  
>  	if (!msg->rx_buf) {
>  		DRM_ERROR("dsi receive buffer size may be NULL\n");
> -		return -EINVAL;
> +		recv_cnt = -EINVAL;
> +		goto restore_dsi_mode;
>  	}
>  
>  	for (i = 0; i < 16; i++)
> @@ -933,6 +943,12 @@ static ssize_t mtk_dsi_host_transfer(struct
> mipi_dsi_host *host,
>  	DRM_INFO("dsi get %d byte data from the panel address(0x%x)\n",
>  		 recv_cnt, *((u8 *)(msg->tx_buf)));
>  
> +restore_dsi_mode:
> +	if (dsi_mode & MODE) {
> +		mtk_dsi_set_mode(dsi);
> +		mtk_dsi_start(dsi);
> +	}
> +
>  	return recv_cnt;
>  }
>