media: sti: bdisp: fix a possible sleep-in-atomic-context bug in bdisp_device_run()

BugLink: https://bugs.launchpad.net/bugs/1868627

[ Upstream commit bb6d4206 ]

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/media/platform/sti/bdisp/bdisp-hw.c, 385:
    msleep in bdisp_hw_reset
drivers/media/platform/sti/bdisp/bdisp-v4l2.c, 341:
    bdisp_hw_reset in bdisp_device_run
drivers/media/platform/sti/bdisp/bdisp-v4l2.c, 317:
    _raw_spin_lock_irqsave in bdisp_device_run

To fix this bug, msleep() is replaced with udelay().

This bug is found by a static analysis tool STCheck written by myself.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

drivers/media/platform/sti/bdisp/bdisp-hw.c

@@ -14,8 +14,8 @@
 #define MAX_SRC_WIDTH           2048
 
 /* Reset & boot poll config */
-#define POLL_RST_MAX            50
-#define POLL_RST_DELAY_MS       20
+#define POLL_RST_MAX            500
+#define POLL_RST_DELAY_MS       2
 
 enum bdisp_target_plan {
 	BDISP_RGB,
@@ -77,7 +77,7 @@ int bdisp_hw_reset(struct bdisp_dev *bdisp)
 	for (i = 0; i < POLL_RST_MAX; i++) {
 		if (readl(bdisp->regs + BLT_STA1) & BLT_STA1_IDLE)
 			break;
-		msleep(POLL_RST_DELAY_MS);
+		udelay(POLL_RST_DELAY_MS * 1000);
 	}
 	if (i == POLL_RST_MAX)
 		dev_err(bdisp->dev, "Reset timeout\n");