From 22bcf27ea280c59152983e9d78506c643ad6226b Mon Sep 17 00:00:00 2001
From: Dom Cobley <popcornmix@gmail.com>
Date: Mon, 13 Jun 2022 16:47:46 +0200
Subject: drm/vc4: hdmi: Clear unused infoframe packet RAM registers
Git-commit: b6079d1578dc4b4b8050d613a5449a63def7d1dd
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849
Using a hdmi analyser the bytes in packet ram
registers beyond the length were visible in the
infoframes and it flagged the checksum as invalid.
Zeroing unused words of packet RAM avoids this
Fixes: 21317b3fba54 ("drm/vc4: Set up the AVI and SPD infoframes.")
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Link: https://lore.kernel.org/r/20220613144800.326124-20-maxime@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index e314e0a4c4c3..ecd49214bd92 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -461,9 +461,11 @@ static void vc4_hdmi_write_infoframe(struct drm_encoder *encoder,
const struct vc4_hdmi_register *ram_packet_start =
&vc4_hdmi->variant->registers[HDMI_RAM_PACKET_START];
u32 packet_reg = ram_packet_start->offset + VC4_HDMI_PACKET_STRIDE * packet_id;
+ u32 packet_reg_next = ram_packet_start->offset +
+ VC4_HDMI_PACKET_STRIDE * (packet_id + 1);
void __iomem *base = __vc4_hdmi_get_field_base(vc4_hdmi,
ram_packet_start->reg);
- uint8_t buffer[VC4_HDMI_PACKET_STRIDE];
+ uint8_t buffer[VC4_HDMI_PACKET_STRIDE] = {};
unsigned long flags;
ssize_t len, i;
int ret;
@@ -499,6 +501,13 @@ static void vc4_hdmi_write_infoframe(struct drm_encoder *encoder,
packet_reg += 4;
}
+ /*
+ * clear remainder of packet ram as it's included in the
+ * infoframe and triggers a checksum error on hdmi analyser
+ */
+ for (; packet_reg < packet_reg_next; packet_reg += 4)
+ writel(0, base + packet_reg);
+
HDMI_WRITE(HDMI_RAM_PACKET_CONFIG,
HDMI_READ(HDMI_RAM_PACKET_CONFIG) | BIT(packet_id));
--
2.38.1