linux-kernel - [PATCH 5.11 192/775] drm/fourcc: fix Amlogic format modifier masks

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Date:   Mon,  1 Mar 2021 17:06:00 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Simon Ser <contact@...rsion.fr>,
        Neil Armstrong <narmstrong@...libre.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Kevin Hilman <khilman@...libre.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 192/775] drm/fourcc: fix Amlogic format modifier masks

From: Simon Ser <contact@...rsion.fr>

[ Upstream commit cc3283f8f41f741fbaef63d0503d8fb4a7919100 ]

The comment says the layout and options use 8 bits, and the shift
uses 8 bits. However the mask is 0xf, ie. 0b00001111 (4 bits).

This could be surprising when introducing new layouts or options
that take more than 4 bits, as this would silently drop the high
bits.

Make the masks consistent with the comment and the shift.

Found when writing a drm_info patch [1].

[1]: https://github.com/ascent12/drm_info/pull/67

Signed-off-by: Simon Ser <contact@...rsion.fr>
Fixes: d6528ec88309 ("drm/fourcc: Add modifier definitions for describing Amlogic Video Framebuffer Compression")
Cc: Neil Armstrong <narmstrong@...libre.com>
Cc: Sam Ravnborg <sam@...nborg.org>
Cc: Kevin Hilman <khilman@...libre.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Acked-by: Neil Armstrong <narmstrong@...libre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210110125103.15447-1-contact@emersion.fr
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/uapi/drm/drm_fourcc.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index 723c8e23ca87d..5f42a14481bd4 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -1036,9 +1036,9 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
  * Not all combinations are valid, and different SoCs may support different
  * combinations of layout and options.
  */
-#define __fourcc_mod_amlogic_layout_mask 0xf
+#define __fourcc_mod_amlogic_layout_mask 0xff
 #define __fourcc_mod_amlogic_options_shift 8
-#define __fourcc_mod_amlogic_options_mask 0xf
+#define __fourcc_mod_amlogic_options_mask 0xff
 
 #define DRM_FORMAT_MOD_AMLOGIC_FBC(__layout, __options) \
 	fourcc_mod_code(AMLOGIC, \
-- 
2.27.0