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From: Damian Kos <dkos@cadence.com>
To: "Chris Zhong" <zyw@rock-chips.com>,
	"Sandy Huang" <hjc@rock-chips.com>,
	"Heiko Stübner" <heiko@sntech.de>,
	"David Airlie" <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: Damian Kos <dkos@cadence.com>
Subject: [PATCH] drm/rockchip: fix for mailbox read size
Date: Tue, 6 Nov 2018 15:37:05 +0000	[thread overview]
Message-ID: <1541518625-25984-1-git-send-email-dkos@cadence.com> (raw)

Some of the functions (like cdn_dp_dpcd_read, cdn_dp_get_edid_block)
allow to read 64KiB, but the cdn_dp_mailbox_read_receive, that is
used by them, can read only up to 255 bytes at once. Normally, it's
not a big issue as DPCD or EDID reads won't (hopefully) exceed that
value.
The real issue here is the revocation list read during the HDCP
authentication process. (problematic use case:
https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.4/drivers/gpu/drm/rockchip/cdn-dp-reg.c#1152)
The list can reach 127*5+4 bytes (num devs * 5 bytes per ID/Bksv +
4 bytes of an additional info).
In other words - CTSes with HDCP Repeater won't pass without this
fix. Oh, and the driver will most likely stop working (best case
scenario).

Signed-off-by: Damian Kos <dkos@cadence.com>
---
 drivers/gpu/drm/rockchip/cdn-dp-reg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
index 3105965fc260..5a485489a1e2 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
@@ -147,7 +147,7 @@ static int cdn_dp_mailbox_validate_receive(struct cdn_dp_device *dp,
 }
 
 static int cdn_dp_mailbox_read_receive(struct cdn_dp_device *dp,
-				       u8 *buff, u8 buff_size)
+				       u8 *buff, u16 buff_size)
 {
 	u32 i;
 	int ret;
-- 
2.17.1


WARNING: multiple messages have this Message-ID (diff)
From: dkos@cadence.com (Damian Kos)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] drm/rockchip: fix for mailbox read size
Date: Tue, 6 Nov 2018 15:37:05 +0000	[thread overview]
Message-ID: <1541518625-25984-1-git-send-email-dkos@cadence.com> (raw)

Some of the functions (like cdn_dp_dpcd_read, cdn_dp_get_edid_block)
allow to read 64KiB, but the cdn_dp_mailbox_read_receive, that is
used by them, can read only up to 255 bytes at once. Normally, it's
not a big issue as DPCD or EDID reads won't (hopefully) exceed that
value.
The real issue here is the revocation list read during the HDCP
authentication process. (problematic use case:
https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.4/drivers/gpu/drm/rockchip/cdn-dp-reg.c#1152)
The list can reach 127*5+4 bytes (num devs * 5 bytes per ID/Bksv +
4 bytes of an additional info).
In other words - CTSes with HDCP Repeater won't pass without this
fix. Oh, and the driver will most likely stop working (best case
scenario).

Signed-off-by: Damian Kos <dkos@cadence.com>
---
 drivers/gpu/drm/rockchip/cdn-dp-reg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
index 3105965fc260..5a485489a1e2 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
@@ -147,7 +147,7 @@ static int cdn_dp_mailbox_validate_receive(struct cdn_dp_device *dp,
 }
 
 static int cdn_dp_mailbox_read_receive(struct cdn_dp_device *dp,
-				       u8 *buff, u8 buff_size)
+				       u8 *buff, u16 buff_size)
 {
 	u32 i;
 	int ret;
-- 
2.17.1

             reply	other threads:[~2018-11-06 15:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-06 15:37 Damian Kos [this message]
2018-11-06 15:37 ` [PATCH] drm/rockchip: fix for mailbox read size Damian Kos
2018-11-19 14:18 ` Heiko Stuebner
2018-11-19 14:18   ` Heiko Stuebner
2018-11-19 14:18   ` Heiko Stuebner

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