media: s5p-cec: add NACK detection support
The s5p-cec driver returned CEC_TX_STATUS_ERROR for the NACK condition.
Some digging into the datasheet uncovered the S5P_CEC_TX_STAT1 register where
bit 0 indicates if the transmit was nacked or not.
Use this to return the correct CEC_TX_STATUS_NACK status to userspace.
This was the only driver that couldn't tell a NACK from another error, and
that was very unusual. And a potential problem for applications as well.
Tested with my Odroid-U3.
Signed-off-by: Hans Verkuil <[email protected]>
Acked-by: Sylwester Nawrocki <[email protected]>
Cc: <[email protected]> # for v4.12 and up
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
diff --git a/drivers/media/platform/s5p-cec/exynos_hdmi_cecctrl.c b/drivers/media/platform/s5p-cec/exynos_hdmi_cecctrl.c
index 1edf667..146ae6f 100644
--- a/drivers/media/platform/s5p-cec/exynos_hdmi_cecctrl.c
+++ b/drivers/media/platform/s5p-cec/exynos_hdmi_cecctrl.c
@@ -172,7 +172,8 @@ u32 s5p_cec_get_status(struct s5p_cec_dev *cec)
{
u32 status = 0;
- status = readb(cec->reg + S5P_CEC_STATUS_0);
+ status = readb(cec->reg + S5P_CEC_STATUS_0) & 0xf;
+ status |= (readb(cec->reg + S5P_CEC_TX_STAT1) & 0xf) << 4;
status |= readb(cec->reg + S5P_CEC_STATUS_1) << 8;
status |= readb(cec->reg + S5P_CEC_STATUS_2) << 16;
status |= readb(cec->reg + S5P_CEC_STATUS_3) << 24;
