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drm/vc4: hdmi: Clear unused infoframe packet RAM registers

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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>
This commit is contained in:
Dom Cobley 2022-06-13 16:47:46 +02:00 committed by Maxime Ripard
parent 25eb441d55
commit b6079d1578
No known key found for this signature in database
GPG Key ID: E3EF0D6F671851C5
1 changed files with 10 additions and 1 deletions
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11
drivers/gpu/drm/vc4/vc4_hdmi.c
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@ -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));