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([2405:201:d019:4042:962d:7736:8598:eb91]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29b5b111e01sm32720885ad.7.2025.11.20.10.02.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Nov 2025 10:02:57 -0800 (PST) From: Sukrut Heroorkar To: Helge Deller , Sukrut Heroorkar , linux-fbdev@vger.kernel.org (open list:FRAMEBUFFER LAYER), dri-devel@lists.freedesktop.org (open list:FRAMEBUFFER LAYER), linux-kernel@vger.kernel.org (open list) Cc: shuah@kernel.org, david.hunter.linux@gamil.com Subject: [RFC/RFT PATCH] fbdev: q40fb: request memory region Date: Thu, 20 Nov 2025 23:32:27 +0530 Message-ID: <20251120180233.763975-1-hsukrut3@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The q40fb driver uses a fixed physical address but never reserves the corresponding I/O region. Reserve the range as suggested in Documentation/gpu/todo.rst ("Request memory regions in all fbdev drivers"). If the memory cannot be reserved, fail probe with -EBUSY to avoid conflicting with another user of the same address. Signed-off-by: Sukrut Heroorkar --- Testing: This patch is sent as RFT since Q40 hardware is unavilable and =20 QEMU does not emulated a Q40 platform. The change is therefore compile-test= ed only. drivers/video/fbdev/q40fb.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/video/fbdev/q40fb.c b/drivers/video/fbdev/q40fb.c index 1ff8fa176124..7b5c31745041 100644 --- a/drivers/video/fbdev/q40fb.c +++ b/drivers/video/fbdev/q40fb.c @@ -101,6 +101,13 @@ static int q40fb_probe(struct platform_device *dev) info->par =3D NULL; info->screen_base =3D (char *) q40fb_fix.smem_start; =20 + if (!request_mem_region(q40fb_fix.smem_start, q40fb_fix.smem_len, + "q40fb")) { + dev_err(&dev->dev, "cannot reserve video memory at 0x%lx\n", + q40fb_fix.smem_start); + return -EBUSY; + } + if (fb_alloc_cmap(&info->cmap, 256, 0) < 0) { framebuffer_release(info); return -ENOMEM; --=20 2.43.0