target/linux/bcm27xx/patches-5.15/950-0430-vc4-Clear-unused-infoframe-packet-RAM-registers.patch

   1 From ce3b4ee2f7d315dadd56ba19587b58339e5d6185 Mon Sep 17 00:00:00 2001
   2 From: Dom Cobley <popcornmix@gmail.com>
   3 Date: Tue, 10 Nov 2020 20:04:08 +0000
   4 Subject: [PATCH] vc4: Clear unused infoframe packet RAM registers
   5
   6 Using a hdmi analyser the bytes in packet ram
   7 registers beyond the length were visible in the
   8 infoframes and it flagged the checksum as invalid.
   9
  10 Zeroing unused words of packet RAM avoids this
  11
  12 Signed-off-by: Dom Cobley <popcornmix@gmail.com>
  13 ---
  14  drivers/gpu/drm/vc4/vc4_hdmi.c | 11 ++++++++++-
  15  1 file changed, 10 insertions(+), 1 deletion(-)
  16
  17 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
  18 +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
  19 @@ -440,9 +440,11 @@ static void vc4_hdmi_write_infoframe(str
  20         const struct vc4_hdmi_register *ram_packet_start =
  21                 &vc4_hdmi->variant->registers[HDMI_RAM_PACKET_START];
  22         u32 packet_reg = ram_packet_start->offset + VC4_HDMI_PACKET_STRIDE * packet_id;
  23 +       u32 packet_reg_next = ram_packet_start->offset +
  24 +               VC4_HDMI_PACKET_STRIDE * (packet_id + 1);
  25         void __iomem *base = __vc4_hdmi_get_field_base(vc4_hdmi,
  26                                                        ram_packet_start->reg);
  27 -       uint8_t buffer[VC4_HDMI_PACKET_STRIDE];
  28 +       uint8_t buffer[VC4_HDMI_PACKET_STRIDE] = {};
  29         unsigned long flags;
  30         ssize_t len, i;
  31         int ret;
  32 @@ -478,6 +480,13 @@ static void vc4_hdmi_write_infoframe(str
  33                 packet_reg += 4;
  34         }
  35
  36 +       /*
  37 +        * clear remainder of packet ram as it's included in the
  38 +        * infoframe and triggers a checksum error on hdmi analyser
  39 +        */
  40 +       for (; packet_reg < packet_reg_next; packet_reg += 4)
  41 +               writel(0, base + packet_reg);
  42 +
  43         HDMI_WRITE(HDMI_RAM_PACKET_CONFIG,
  44                    HDMI_READ(HDMI_RAM_PACKET_CONFIG) | BIT(packet_id));
  45