[PATCH 4.17 010/324] drm/bridge/sii8620: fix loops in EDID fetch logic

Greg Kroah-Hartman
2018-08-23T08:41:11Z

From: Andrzej Hajda <a.hajda@samsung.com>

[ Upstream commit 8e627a1b1ce8feb3e1da4428b71b9b4905f04888 ]

Function should constantly check if cable is connected and finish
in finite time.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Maciej Purski <m.purski@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180115173357.31067-4-a.hajda@samsung.com
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/bridge/sil-sii8620.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/bridge/sil-sii8620.c
+++ b/drivers/gpu/drm/bridge/sil-sii8620.c
@@ -807,6 +807,7 @@ static void sii8620_burst_rx_all(struct
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;
@@ -856,23 +857,31 @@ static void sii8620_fetch_edid(struct si
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) {