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Wed, 22 Jan 2020 14:14:38 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 22 Jan 2020 19:44:38 +0530 From: Sai Prakash Ranjan To: Rob Clark , Douglas Anderson Cc: Matthias Kaehlcke , Stephen Boyd , Sean Paul , Sean Paul , linux-arm-msm , Linux Kernel Mailing List , dri-devel , David Airlie , freedreno , Daniel Vetter Subject: Re: [REPOST PATCH] drm/msm: Set dma maximum segment size for mdss In-Reply-To: References: <20200121111813.REPOST.1.I92c66a35fb13f368095b05287bdabdbe88ca6922@changeid> Message-ID: <74a88f1a4d2ce17e25ecb52b8d1ccbc1@codeaurora.org> X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2020-01-22 00:56, Rob Clark wrote: > On Tue, Jan 21, 2020 at 11:19 AM Douglas Anderson > wrote: >> >> From: Sean Paul >> >> Turning on CONFIG_DMA_API_DEBUG_SG results in the following error: >> >> [ 12.078665] msm ae00000.mdss: DMA-API: mapping sg segment longer >> than device claims to support [len=3526656] [max=65536] >> [ 12.089870] WARNING: CPU: 6 PID: 334 at >> /mnt/host/source/src/third_party/kernel/v4.19/kernel/dma/debug.c:1301 >> debug_dma_map_sg+0x1dc/0x318 >> [ 12.102655] Modules linked in: joydev >> [ 12.106442] CPU: 6 PID: 334 Comm: frecon Not tainted 4.19.0 #2 >> [ 12.112450] Hardware name: Google Cheza (rev3+) (DT) >> [ 12.117566] pstate: 60400009 (nZCv daif +PAN -UAO) >> [ 12.122506] pc : debug_dma_map_sg+0x1dc/0x318 >> [ 12.126995] lr : debug_dma_map_sg+0x1dc/0x318 >> [ 12.131487] sp : ffffff800cc3ba80 >> [ 12.134913] x29: ffffff800cc3ba80 x28: 0000000000000000 >> [ 12.140395] x27: 0000000000000004 x26: 0000000000000004 >> [ 12.145868] x25: ffffff8008e55b18 x24: 0000000000000000 >> [ 12.151337] x23: 00000000ffffffff x22: ffffff800921c000 >> [ 12.156809] x21: ffffffc0fa75b080 x20: ffffffc0f7195090 >> [ 12.162280] x19: ffffffc0f1c53280 x18: 0000000000000000 >> [ 12.167749] x17: 0000000000000000 x16: 0000000000000000 >> [ 12.173218] x15: 0000000000000000 x14: 0720072007200720 >> [ 12.178689] x13: 0720072007200720 x12: 0720072007200720 >> [ 12.184161] x11: 0720072007200720 x10: 0720072007200720 >> [ 12.189641] x9 : ffffffc0f1fc6b60 x8 : 0000000000000000 >> [ 12.195110] x7 : ffffff8008132ce0 x6 : 0000000000000000 >> [ 12.200585] x5 : 0000000000000000 x4 : ffffff8008134734 >> [ 12.206058] x3 : ffffff800cc3b830 x2 : ffffffc0f1fc6240 >> [ 12.211532] x1 : 25045a74f48a7400 x0 : 25045a74f48a7400 >> [ 12.217006] Call trace: >> [ 12.219535] debug_dma_map_sg+0x1dc/0x318 >> [ 12.223671] get_pages+0x19c/0x20c >> [ 12.227177] msm_gem_fault+0x64/0xfc >> [ 12.230874] __do_fault+0x3c/0x140 >> [ 12.234383] __handle_mm_fault+0x70c/0xdb8 >> [ 12.238603] handle_mm_fault+0xac/0xc4 >> [ 12.242473] do_page_fault+0x1bc/0x3d4 >> [ 12.246342] do_translation_fault+0x54/0x88 >> [ 12.250652] do_mem_abort+0x60/0xf0 >> [ 12.254250] el0_da+0x20/0x24 >> [ 12.257317] irq event stamp: 67260 >> [ 12.260828] hardirqs last enabled at (67259): [] >> console_unlock+0x214/0x608 >> [ 12.269693] hardirqs last disabled at (67260): [] >> do_debug_exception+0x5c/0x178 >> [ 12.278820] softirqs last enabled at (67256): [] >> __do_softirq+0x4d4/0x520 >> [ 12.287510] softirqs last disabled at (67249): [] >> irq_exit+0xa8/0x100 >> [ 12.295742] ---[ end trace e63cfc40c313ffab ]--- >> >> The root of the problem is that the default segment size for sgt is >> (UINT_MAX & PAGE_MASK), and the default segment size for device dma is >> 64K. As such, if you compare the 2, you would deduce that the sg >> segment >> will overflow the device's capacity. In reality, the hardware can >> accommodate the larger sg segments, it's just not initializing its max >> segment properly. This patch initializes the max segment size for the >> mdss device, which gets rid of that pesky warning. >> >> Reported-by: Stephen Boyd >> Signed-off-by: Sean Paul >> Tested-by: Stephen Boyd >> Signed-off-by: Douglas Anderson >> --- >> This patch has been floating in the ether for over a year [1]. I know >> next to nothing about it, but I'm told it's still useful so I'm >> helpfully reposting it. Please enjoy. > > This looks like the right thing to do.. sorry I overlooked the patch > first time around > > Reviewed-by: Rob Clark > > (since I've already sent PR for msm-next, could we pick this up via > drm-misc?) > This also fixes a similar warning seen on SC7180 during video playback. Tested-by: Sai Prakash Ranjan Logs for reference, localhost ~ # [ 647.100504] ------------[ cut here ]------------ [ 647.105748] DMA-API: msm ae00000.mdss: mapping sg segment longer than device claims to support [len=524288] [max=65536] <...snip...> [ 647.184254] pstate: 60400009 (nZCv daif +PAN -UAO) [ 647.189211] pc : debug_dma_map_sg+0x1a8/0x2c4 [ 647.193708] lr : debug_dma_map_sg+0x1a8/0x2c4 [ 647.198202] sp : ffffffc010f6ba80 [ 647.201626] x29: ffffffc010f6ba90 x28: 0000000000010000 [ 647.207110] x27: 00000000ffffffff x26: ffffff8174840b80 [ 647.212592] x25: ffffffe9f4fe5000 x24: 0000000000000003 [ 647.218075] x23: ffffff815c223780 x22: ffffff81742d0810 [ 647.223557] x21: 0000000000000003 x20: 0000000000000001 [ 647.229041] x19: 0000000000000001 x18: 0000000000000000 [ 647.234524] x17: 000000000000003c x16: ffffffe9f4444a14 [ 647.240006] x15: 0000000000000006 x14: 0720072007200720 [ 647.245489] x13: 0720072007200720 x12: 0000000000000000 [ 647.250969] x11: 0000000000000000 x10: 0000000000000000 [ 647.256452] x9 : 4be0233cf8ef6200 x8 : 4be0233cf8ef6200 [ 647.261935] x7 : 0720072007200720 x6 : ffffff8175ea0f00 [ 647.267417] x5 : 0000000000000000 x4 : 0000000000000000 [ 647.272898] x3 : 0000000000000000 x2 : ffffff81771d1680 [ 647.278380] x1 : ffffff81771c10c0 x0 : 000000000000006b [ 647.283863] Call trace: [ 647.286409] debug_dma_map_sg+0x1a8/0x2c4 [ 647.290569] vb2_dma_sg_dmabuf_ops_map+0x138/0x18c [videobuf2_dma_sg] [ 647.297215] dma_buf_map_attachment+0x6c/0xb0 [ 647.301724] drm_gem_prime_import_dev+0xa4/0x134 [ 647.306495] drm_gem_prime_fd_to_handle+0xc4/0x194 [ 647.311444] drm_prime_fd_to_handle_ioctl+0x40/0x58 [ 647.316483] drm_ioctl_kernel+0x94/0x10c [ 647.320538] drm_ioctl+0x264/0x3f8 [ 647.324059] drm_compat_ioctl+0xcc/0xdc [ 647.328033] __se_compat_sys_ioctl+0x100/0x2074 [ 647.332715] __arm64_compat_sys_ioctl+0x20/0x2c [ 647.337406] el0_svc_common+0xa4/0x154 [ 647.341279] el0_svc_compat_handler+0x2c/0x38 [ 647.345781] el0_svc_compat+0x8/0x10 [ 647.349474] ---[ end trace 2f188eb70b295b6c ]--- [ 648.282197] ------------[ cut here ]------------ Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation