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Fri, 14 Jun 2024 00:24:28 +0200 Message-ID: <64bbb753-ec26-41ca-a585-fb74ae9e854c@gmx.de> Date: Fri, 14 Jun 2024 00:24:26 +0200 Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fbdev: vesafb: Detect VGA compatibility from screen info's VESA attributes To: Javier Martinez Canillas , Thomas Zimmermann , sam@ravnborg.org, hpa@zytor.com Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, stable@vger.kernel.org References: <20240613090240.7107-1-tzimmermann@suse.de> <5d8d2efe-45dd-4033-aaae-e7f923ef9e76@gmx.de> <87tthwqzq2.fsf@minerva.mail-host-address-is-not-set> Content-Language: en-US From: Helge Deller Autocrypt: addr=deller@gmx.de; keydata= xsFNBF3Ia3MBEAD3nmWzMgQByYAWnb9cNqspnkb2GLVKzhoH2QD4eRpyDLA/3smlClbeKkWT HLnjgkbPFDmcmCz5V0Wv1mKYRClAHPCIBIJgyICqqUZo2qGmKstUx3pFAiztlXBANpRECgwJ r+8w6mkccOM9GhoPU0vMaD/UVJcJQzvrxVHO8EHS36aUkjKd6cOpdVbCt3qx8cEhCmaFEO6u CL+k5AZQoABbFQEBocZE1/lSYzaHkcHrjn4cQjc3CffXnUVYwlo8EYOtAHgMDC39s9a7S90L 69l6G73lYBD/Br5lnDPlG6dKfGFZZpQ1h8/x+Qz366Ojfq9MuuRJg7ZQpe6foiOtqwKym/zV dVvSdOOc5sHSpfwu5+BVAAyBd6hw4NddlAQUjHSRs3zJ9OfrEx2d3mIfXZ7+pMhZ7qX0Axlq Lq+B5cfLpzkPAgKn11tfXFxP+hcPHIts0bnDz4EEp+HraW+oRCH2m57Y9zhcJTOJaLw4YpTY GRUlF076vZ2Hz/xMEvIJddRGId7UXZgH9a32NDf+BUjWEZvFt1wFSW1r7zb7oGCwZMy2LI/G aHQv/N0NeFMd28z+deyxd0k1CGefHJuJcOJDVtcE1rGQ43aDhWSpXvXKDj42vFD2We6uIo9D 1VNre2+uAxFzqqf026H6cH8hin9Vnx7p3uq3Dka/Y/qmRFnKVQARAQABzRxIZWxnZSBEZWxs ZXIgPGRlbGxlckBnbXguZGU+wsGRBBMBCAA7AhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheA FiEERUSCKCzZENvvPSX4Pl89BKeiRgMFAl3J1zsCGQEACgkQPl89BKeiRgNK7xAAg6kJTPje uBm9PJTUxXaoaLJFXbYdSPfXhqX/BI9Xi2VzhwC2nSmizdFbeobQBTtRIz5LPhjk95t11q0s uP5htzNISPpwxiYZGKrNnXfcPlziI2bUtlz4ke34cLK6MIl1kbS0/kJBxhiXyvyTWk2JmkMi REjR84lCMAoJd1OM9XGFOg94BT5aLlEKFcld9qj7B4UFpma8RbRUpUWdo0omAEgrnhaKJwV8 qt0ULaF/kyP5qbI8iA2PAvIjq73dA4LNKdMFPG7Rw8yITQ1Vi0DlDgDT2RLvKxEQC0o3C6O4 iQq7qamsThLK0JSDRdLDnq6Phv+Yahd7sDMYuk3gIdoyczRkXzncWAYq7XTWl7nZYBVXG1D8 gkdclsnHzEKpTQIzn/rGyZshsjL4pxVUIpw/vdfx8oNRLKj7iduf11g2kFP71e9v2PP94ik3 Xi9oszP+fP770J0B8QM8w745BrcQm41SsILjArK+5mMHrYhM4ZFN7aipK3UXDNs3vjN+t0zi qErzlrxXtsX4J6nqjs/mF9frVkpv7OTAzj7pjFHv0Bu8pRm4AyW6Y5/H6jOup6nkJdP/AFDu 5ImdlA0jhr3iLk9s9WnjBUHyMYu+HD7qR3yhX6uWxg2oB2FWVMRLXbPEt2hRGq09rVQS7DBy dbZgPwou7pD8MTfQhGmDJFKm2jvOwU0EXchrcwEQAOsDQjdtPeaRt8EP2pc8tG+g9eiiX9Sh rX87SLSeKF6uHpEJ3VbhafIU6A7hy7RcIJnQz0hEUdXjH774B8YD3JKnAtfAyuIU2/rOGa/v UN4BY6U6TVIOv9piVQByBthGQh4YHhePSKtPzK9Pv/6rd8H3IWnJK/dXiUDQllkedrENXrZp eLUjhyp94ooo9XqRl44YqlsrSUh+BzW7wqwfmu26UjmAzIZYVCPCq5IjD96QrhLf6naY6En3 ++tqCAWPkqKvWfRdXPOz4GK08uhcBp3jZHTVkcbo5qahVpv8Y8mzOvSIAxnIjb+cklVxjyY9 dVlrhfKiK5L+zA2fWUreVBqLs1SjfHm5OGuQ2qqzVcMYJGH/uisJn22VXB1c48yYyGv2HUN5 lC1JHQUV9734I5cczA2Gfo27nTHy3zANj4hy+s/q1adzvn7hMokU7OehwKrNXafFfwWVK3OG 1dSjWtgIv5KJi1XZk5TV6JlPZSqj4D8pUwIx3KSp0cD7xTEZATRfc47Yc+cyKcXG034tNEAc xZNTR1kMi9njdxc1wzM9T6pspTtA0vuD3ee94Dg+nDrH1As24uwfFLguiILPzpl0kLaPYYgB wumlL2nGcB6RVRRFMiAS5uOTEk+sJ/tRiQwO3K8vmaECaNJRfJC7weH+jww1Dzo0f1TP6rUa fTBRABEBAAHCwXYEGAEIACAWIQRFRIIoLNkQ2+89Jfg+Xz0Ep6JGAwUCXchrcwIbDAAKCRA+ Xz0Ep6JGAxtdEAC54NQMBwjUNqBNCMsh6WrwQwbg9tkJw718QHPw43gKFSxFIYzdBzD/YMPH l+2fFiefvmI4uNDjlyCITGSM+T6b8cA7YAKvZhzJyJSS7pRzsIKGjhk7zADL1+PJei9p9idy RbmFKo0dAL+ac0t/EZULHGPuIiavWLgwYLVoUEBwz86ZtEtVmDmEsj8ryWw75ZIarNDhV74s BdM2ffUJk3+vWe25BPcJiaZkTuFt+xt2CdbvpZv3IPrEkp9GAKof2hHdFCRKMtgxBo8Kao6p Ws/Vv68FusAi94ySuZT3fp1xGWWf5+1jX4ylC//w0Rj85QihTpA2MylORUNFvH0MRJx4mlFk XN6G+5jIIJhG46LUucQ28+VyEDNcGL3tarnkw8ngEhAbnvMJ2RTx8vGh7PssKaGzAUmNNZiG MB4mPKqvDZ02j1wp7vthQcOEg08z1+XHXb8ZZKST7yTVa5P89JymGE8CBGdQaAXnqYK3/yWf FwRDcGV6nxanxZGKEkSHHOm8jHwvQWvPP73pvuPBEPtKGLzbgd7OOcGZWtq2hNC6cRtsRdDx 4TAGMCz4j238m+2mdbdhRh3iBnWT5yPFfnv/2IjFAk+sdix1Mrr+LIDF++kiekeq0yUpDdc4 ExBy2xf6dd+tuFFBp3/VDN4U0UfG4QJ2fg19zE5Z8dS4jGIbLg== In-Reply-To: <87tthwqzq2.fsf@minerva.mail-host-address-is-not-set> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:TjMHWNSZZcAQQyk6VKxSPHrIpUpHj8lHp6rN7ELjRr34m9iSJl4 +2DuZOCnbWB0DHkNGqzV5KTcnAV3Mp07TMvPO9m6yaj+aahiMI85Vq4ghBYhbWxHsRxgaTb zXaz3skuHXQO/GlRm5VG5cQwcT7ijfRpHk/N62QNtL2k5tSRoEW8Bs6w/6B/c2TQMrgKk/C N3xG6ip6qTwSjFasC5/Ug== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:spuUaHxCHPk=;2SjzIO9i4oxv8/LltaNQeSBccHq Hd+VCvLI3goo5W463P3U4N/fTsvgGgs3qCGPx2Jqv4g6V9tbAO92EXM8zq5/QTbbieAl1rk+c ERk1U+wivXbTBFlBfFR5Xb45mDKVU9BfLxhUVIae6jbOxEItYo8yHgp7G42CLSVx/HMnbNGEb 6MLG/C2OIKAtUpWf4pZ0sXeX1CGGRd1NTZKUlYUAXugUskYtp9KXdSIezTivwmMVHXTR4Rm0x YWcvkZUlS2gHs5pSIV2avQevJg/O//q74SaHFgchO9DYpM3iLuto/2YhlQQyL3bvAUSHKV28p djg9y9f+gzAiQJbg19XsaCwBym+1bW91aaPiyM/cDus194ZIuKaWRCobSFvdG5SCMAyCWr2eS KDczFvnP9NWPx0c8zBBOnmQf6o08IJq6q9/rKFwd63XfuqS99K+S+cx+Cck1zq/2UU0dVUIsY irgz7sFBJweCnUcceYnPr1IZVb/ftThGINDTF0G62XvI5WbJF284r55K3xFpeQtxB+ia0tzG/ s/EdmM0DaH7NbRBnfueVohnrydE84OuOBaQtnzc4okyuy1DAKrhLcP4NVnICwzvndRa/WMxEJ d0JufnUCrG5nuvZs8K9eXzzDhZMLVRPMNIAmeUCeyinF5/96qUM2XUiny5D39fbgxTVLl2wmG EshGE9HBei7I8xg5penkadqP4mL86F2wllH5FqAXeINla6RHiolSIvAl4fP8DwcxK+1okypry WU4ubxIBFShZgjKix4PUysZBiJ0ZRRjRXTcIYVEfMeFfju4RbULiIFBPr0Hrgb74VluVw1G9R 9dtgDVyXnvTzUH1MgRLlLHieiHZx9U6ObPS2J7DZj2/nA= On 6/13/24 23:50, Javier Martinez Canillas wrote: > Helge Deller writes: > >> On 6/13/24 11:02, Thomas Zimmermann wrote: >>> Test the vesa_attributes field in struct screen_info for compatibility >>> with VGA hardware. Vesafb currently tests bit 1 in screen_info's >>> capabilities field, It sets the framebuffer address size and is >>> unrelated to VGA. >>> >>> Section 4.4 of the Vesa VBE 2.0 specifications defines that bit 5 in >>> the mode's attributes field signals VGA compatibility. The mode is >>> compatible with VGA hardware if the bit is clear. In that case, the >>> driver can access VGA state of the VBE's underlying hardware. The >>> vesafb driver uses this feature to program the color LUT in palette >>> modes. Without, colors might be incorrect. >>> >>> The problem got introduced in commit 89ec4c238e7a ("[PATCH] vesafb: Fi= x >>> incorrect logo colors in x86_64"). It incorrectly stores the mode >>> attributes in the screen_info's capabilities field and updates vesafb >>> accordingly. Later, commit 5e8ddcbe8692 ("Video mode probing support f= or >>> the new x86 setup code") fixed the screen_info, but did not update ves= afb. >>> Color output still tends to work, because bit 1 in capabilities is >>> usually 0. >>> >>> Besides fixing the bug in vesafb, this commit introduces a helper that >>> reads the correct bit from screen_info. >> >> Nice catch, Thomas! >> >> But do we really need this additional helper? >> >> >>> >>> Signed-off-by: Thomas Zimmermann >>> Fixes: 5e8ddcbe8692 ("Video mode probing support for the new x86 setup= code") >>> Cc: # v2.6.23+ >> >>> --- >>> drivers/video/fbdev/vesafb.c | 2 +- >>> include/linux/screen_info.h | 5 +++++ >>> 2 files changed, 6 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb= .c >>> index 8ab64ae4cad3e..5a161750a3aee 100644 >>> --- a/drivers/video/fbdev/vesafb.c >>> +++ b/drivers/video/fbdev/vesafb.c >>> @@ -271,7 +271,7 @@ static int vesafb_probe(struct platform_device *de= v) >>> if (si->orig_video_isVGA !=3D VIDEO_TYPE_VLFB) >>> return -ENODEV; >>> >>> - vga_compat =3D (si->capabilities & 2) ? 0 : 1; >>> + vga_compat =3D !__screen_info_vbe_mode_nonvga(si); >> >> Instead maybe just this: ? >> + /* mode is VGA-compatible if BIT 5 is _NOT_ set */ >> + vga_compat =3D (si->vesa_attributes & BIT(5)) =3D=3D 0; >> >> I suggest to make patch small, esp. if you ask for backport to v2.6.23+= . >> > > I prefer the helper. It's a static inline anyways and having it as a > function makes it much easier to read / understand. Really? +static inline bool __screen_info_vbe_mode_nonvga(const struct screen_info= *si) +{ + return si->vesa_attributes & BIT(5); // VGA if _not_ set +} At least the double negation "!nonvga()" breaks my head and the "//" comme= nt should be converted to /*..*/ IMHO. Helge