[PATCH 3/3] drm/bridge/sii8620: fix loops in EDID fetch logic

[Marek Szyprowski]

Hi Andrzej,

On 2018-01-15 18:33, Andrzej Hajda wrote:
> Function should constantly check if cable is connected and finish
> in finite time.
>
> Signed-off-by: Andrzej Hajda <a.hajda at samsung.com>

Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>

> ---
>   drivers/gpu/drm/bridge/sil-sii8620.c | 31 ++++++++++++++++++++-----------
>   1 file changed, 20 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
> index 7c46847fef18..f65e14836c0e 100644
> --- a/drivers/gpu/drm/bridge/sil-sii8620.c
> +++ b/drivers/gpu/drm/bridge/sil-sii8620.c
> @@ -801,6 +801,7 @@ static void sii8620_burst_rx_all(struct sii8620 *ctx)
>   static void sii8620_fetch_edid(struct sii8620 *ctx)
>   {
>   	u8 lm_ddc, ddc_cmd, int3, cbus;
> +	unsigned long timeout;
>   	int fetched, i;
>   	int edid_len = EDID_LENGTH;
>   	u8 *edid;
> @@ -850,23 +851,31 @@ static void sii8620_fetch_edid(struct sii8620 *ctx)
>   			REG_DDC_CMD, ddc_cmd | VAL_DDC_CMD_ENH_DDC_READ_NO_ACK
>   		);
>   
> -		do {
> -			int3 = sii8620_readb(ctx, REG_INTR3);
> +		int3 = 0;
> +		timeout = jiffies + msecs_to_jiffies(200);
> +		for (;;) {
>   			cbus = sii8620_readb(ctx, REG_CBUS_STATUS);
> -
> -			if (int3 & BIT_DDC_CMD_DONE)
> -				break;
> -
> -			if (!(cbus & BIT_CBUS_STATUS_CBUS_CONNECTED)) {
> +			if (~cbus & BIT_CBUS_STATUS_CBUS_CONNECTED) {
> +				kfree(edid);
> +				edid = NULL;
> +				goto end;
> +			}
> +			if (int3 & BIT_DDC_CMD_DONE) {
> +				if (sii8620_readb(ctx, REG_DDC_DOUT_CNT)
> +				    >= FETCH_SIZE)
> +					break;
> +			} else {
> +				int3 = sii8620_readb(ctx, REG_INTR3);
> +			}
> +			if (time_is_before_jiffies(timeout)) {
> +				ctx->error = -ETIMEDOUT;
> +				dev_err(ctx->dev, "timeout during EDID read\n");
>   				kfree(edid);
>   				edid = NULL;
>   				goto end;
>   			}
> -		} while (1);
> -
> -		sii8620_readb(ctx, REG_DDC_STATUS);
> -		while (sii8620_readb(ctx, REG_DDC_DOUT_CNT) < FETCH_SIZE)
>   			usleep_range(10, 20);
> +		}
>   
>   		sii8620_read_buf(ctx, REG_DDC_DATA, edid + fetched, FETCH_SIZE);
>   		if (fetched + FETCH_SIZE == EDID_LENGTH) {

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