[PATCH v2 03/15] drm/vc4: hdmi: Fix register offset with longer CEC messages

Maxime Ripard
2021-01-11T14:25:00Z

From: Dom Cobley <popcornmix@gmail.com>

The code prior to 311e305fdb4e ("drm/vc4: hdmi: Implement a register
layout abstraction") was relying on the fact that the register offset
was incremented by 4 for each readl call. That worked since the register
width is 4 bytes.

However, since that commit the HDMI_READ macro is now taking an enum,
and the offset doesn't increment by 4 but 1 now. Divide the index by 4
to fix this.

Fixes: 311e305fdb4e ("drm/vc4: hdmi: Implement a register layout abstraction")
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index cb4594e7df6f..7945dbcee78c 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1443,13 +1443,20 @@ static irqreturn_t vc4_cec_irq_handler_thread(int irq, void *priv)

static void vc4_cec_read_msg(struct vc4_hdmi *vc4_hdmi, u32 cntrl1)
{
+ struct drm_device *dev = vc4_hdmi->connector.dev;
struct cec_msg *msg = &vc4_hdmi->cec_rx_msg;
unsigned int i;

msg->len = 1 + ((cntrl1 & VC4_HDMI_CEC_REC_WRD_CNT_MASK) >>
VC4_HDMI_CEC_REC_WRD_CNT_SHIFT);
+
+ if (msg->len > 16) {
+ drm_err(dev, "Attempting to read too much data (%d)\n", msg->len);
+ return;
+ }
+
for (i = 0; i < msg->len; i += 4) {
- u32 val = HDMI_READ(HDMI_CEC_RX_DATA_1 + i);
+ u32 val = HDMI_READ(HDMI_CEC_RX_DATA_1 + (i >> 2));

msg->msg[i] = val & 0xff;
msg->msg[i + 1] = (val >> 8) & 0xff;
@@ -1542,11 +1549,17 @@ static int vc4_hdmi_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
u32 signal_free_time, struct cec_msg *msg)
{
struct vc4_hdmi *vc4_hdmi = cec_get_drvdata(adap);
+ struct drm_device *dev = vc4_hdmi->connector.dev;
u32 val;
unsigned int i;

+ if (msg->len > 16) {
+ drm_err(dev, "Attempting to transmit too much data (%d)\n", msg->len);
+ return -ENOMEM;
+ }
+
for (i = 0; i < msg->len; i += 4)
- HDMI_WRITE(HDMI_CEC_TX_DATA_1 + i,
+ HDMI_WRITE(HDMI_CEC_TX_DATA_1 + (i >> 2),
(msg->msg[i]) |
(msg->msg[i + 1] << 8) |
(msg->msg[i + 2] << 16) |
--
2.29.2