Linux/AM5728: SGX544 compositing direct output to GC320

Tool/software: Linux

I need to rotate the output of the SGX544 OpenGL rendering cycle using the GC320. I have it working, but right now it requires 1 memcpy. I need to have zero copies for this operation.
The problem is that I cannot call the GC320 gcoSURF_SetBuffer() function with the memory mapped pointer from OpenGL's GEM BO backing store. If I do this, I immediately get an unrecoverable Linux Kernel GC320 Driver exception and have to reset the board. I have to copy it first, and call gcoSURF_SetBuffer() with the destination pointer of the copy operation.

Another interesting point is that if I memcpy the mmap'ed BO pointer, but then use the original mmap'ed BO pointer passed to gcoSURF_SetBuffer(), it seems to work. Something happens when I memcpy the mmap'ed BO pointer that causes the GC320 driver to be able to use the data with gcoSURF_SetBuffer.

My rendering code looks like this:

m_OGLController->paintGL();

m_OGLController->swapBuffers();

m_NextBo = gbm_surface_lock_front_buffer(m_Gbm->m_GBMSurface);

m_Fb = m_DRMController->drmFbGetFromBo(m_NextBo);

gbm_surface_release_buffer(m_Gbm->m_GBMSurface, m_NextBo);

m_Fb is this structure:

struct drm_fb *m_Fb;
...
// A GBM buffer ( GBM-Buf ) object allocated from the DRM device
// This can be set on a DRM Plane
struct drm_fb {
    struct gbm_bo *bo;
    uint32_t fb_id;
};

The memcpy looks like this:

// Copy data otherwise GC320 Driver Crashes
memcpy(cpyFrame,gpuMmapFrame,dmaBuf.height * dmaBuf.width * 4);

The rotation code that includes the memcpy is contained in this function:

        // Schedule an update
        drmModeAtomicReqPtr req = drmModeAtomicAlloc();

        {

            // This is in a background thread and we want to protect shared vars
            QMutexLocker locker(&m_VSyncMutex);

            // Rotate the frame for LCD using GC320
            dmabuf_buffer dmaBuf = m_DRMController->drmGetDmaBufFromBo(m_Fb->bo);

            // Switch size of backing store based on input argument
            QString selectedDisplay = qApp->property("DESIRED-SCREEN").toString();
            if ( selectedDisplay.toLower() == "lcd" || selectedDisplay.toLower() == "both" ) {

                /* This is a hacky way to mmap the GBM BO.        */
                /* Ideally there should be GBM API to mmap the buffer    */
                /* NOTE: The address obtained is virtual address.    */
                union gbm_bo_handle handleUnion = gbm_bo_get_handle(m_Fb->bo);
                struct drm_omap_gem_info gemInfo;
                char *gpuMmapFrame = NULL;
                gemInfo.handle = handleUnion.s32;
                int ret = drmCommandWriteRead(m_DRMController->m_Fd, DRM_OMAP_GEM_INFO,&gemInfo, sizeof(gemInfo));
                if (ret) {
                    qDebug() << "RenderingManager::drmCommandWriteRead(): Cannot set write/read";
                }
                else {

                    // Mmap the frame
                    gpuMmapFrame = (char *)mmap(0, gemInfo.size, PROT_READ | PROT_WRITE, MAP_SHARED,m_DRMController->m_Fd, gemInfo.offset);

                    if ( gpuMmapFrame && gpuMmapFrame != MAP_FAILED ) {

                        // For now need to copy the frame to rotate it
                        char *cpyFrame = NULL;
                        cpyFrame = (char*)malloc(sizeof(char) * dmaBuf.width * dmaBuf.height * 4);
                        if ( cpyFrame ) {

                            // Copy data otherwise GC320 Driver Crashes
                            memcpy(cpyFrame,gpuMmapFrame,dmaBuf.height * dmaBuf.width * 4);

                            // Perform the rotation with the gc320
                            m_GC320Controller->renderRGBARotate90(cpyFrame, dmaBuf.width, dmaBuf.height);

                            // Get the dmabuf handle
                            quint32 gc320DMABufHandle = m_GC320Controller->getOutputDmaBufHandle();

                            /////////////////////////////////////////////////////////////////////


                            // For each Composited / Rotated DMABUF - import the bo once so we can pass that to the egl image generation
                            struct rotatedBoDmaBuf {
                                gbm_bo *bo;
                                int fd;
                            };

                            // Store the dma buf info
                            rotatedBoDmaBuf rotatedBo;

                            // Setup RGB import data
                            struct gbm_import_fd_data gbm_rotated_dmabuf = {
                                .fd     = gc320DMABufHandle,
                                        .width  = 480,
                                        .height = 800,
                                        .stride = 480 * 4,
                                        .format = GBM_FORMAT_ARGB8888
                            };

                            gbm_device* currentGbmDev = m_OGLController->getGBMDev();
                            rotatedBo.bo = gbm_bo_import(currentGbmDev, GBM_BO_IMPORT_FD, &gbm_rotated_dmabuf, GBM_BO_USE_SCANOUT);

                            drm_fb *rotatedFb = m_DRMController->drmFbGetFromBo(rotatedBo.bo);

                            // Update LCD
                            drmModeAtomicAddProperty(req, m_DRMController->m_DrmPlaneId[3], 14, rotatedFb->fb_id);

                            // Unmap it
                            munmap(gpuMmapFrame,SCREEN_HEIGHT*SCREEN_WIDTH*4);

                            // Free it
                            free(cpyFrame);

                        }

                    }

                }

            }
            else {

                // Update HDMI
                //drmModeAtomicAddProperty(req, m_DRMController->m_DrmPlaneId[3], 14, m_Fb->fb_id);

            }

        }

        // VSync commit
        int ret = drmModeAtomicCommit(m_DRMController->m_Fd, req, DRM_MODE_ATOMIC_TEST_ONLY, 0);
        if(!ret){
            drmModeAtomicCommit(m_DRMController->m_Fd, req, DRM_MODE_PAGE_FLIP_EVENT | DRM_MODE_ATOMIC_NONBLOCK, &m_WaitingForFlip);
        }
        else {
            fprintf(stderr,"RenderingManager::PageFlip: Failed to add plane atomically: %s\n", strerror(errno));
        }
        drmModeAtomicFree(req);

        // Wait for an VSync update
        FD_ZERO(&m_Fds);
        FD_SET(m_DRMController->m_Fd, &m_Fds);

        while (m_WaitingForFlip) {
            ret = select(m_DRMController->m_Fd + 1, &m_Fds, NULL, NULL, NULL);
            if (ret < 0) {
                fprintf(stderr,"RenderingManager::PageFlip: Error - Select err: %s\n", strerror(errno));
                break;
            } else if (ret == 0) {
                fprintf(stderr,"RenderingManager::PageFlip: Error - Select timeout!\n");
                break;
            } else if (FD_ISSET(0, &m_Fds)) {
                fprintf(stderr,"RenderingManager::PageFlip: Warning - User interrupted!\n");
                break;
            }
            drmHandleEvent(m_DRMController->m_Fd, &m_Evctx);
        }

        // Waiting for flip again
        m_WaitingForFlip = 1;

If I do not include the memcpy, and pass the "gpuMmapFrame" directly to the GC320 function, I get the following error on the Linux Kernel console:

[ 8063.964224] Unable to handle kernel paging request at virtual address ffffc53c
[ 8063.971555] pgd = ecd29180
[ 8063.974276] [ffffc53c] *pgd=80000080007003, *pmd=affaa003, *pte=00000000
[ 8063.981060] Internal error: Oops: 207 [#1] PREEMPT SMP ARM
[ 8063.986568] Modules linked in: vfb galcore(O) cfg80211 rpmsg_rpc snd_soc_omap_hdmi_audio snd_soc_omap snd_soc_core snd_pcm_dmaengine snd_pcm snd_timer snd soundcore virtio_rpmsg_bus omapdrm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops panel_dpi encoder_tpd12s015 connector_hdmi omapdss omapdss_base phy_omap_usb2 pruss omap_wdt phy_ti_pipe3 phy_omap_control ti_vpe ti_vip ti_sc ti_csc v4l2_mem2mem ti_vpdma videobuf2_dma_contig videobuf2_memops videobuf2_v4l2 pvrsrvkm(O) videobuf2_core dwc3_omap drm rtc_omap pwm_tiehrpwm flk_ti_mt9p031 comp_mir_hp aptina_pll v4l2_common videodev media rtc_palmas rtc_m41t80 spi_omap2_mcspi omap_remoteproc remoteproc virtio virtio_ring uio_pdrv_genirq uio cryptodev(O) autofs4
[ 8064.051100] CPU: 1 PID: 7282 Comm: Thread (pooled) Tainted: G           O    4.4.41 #1
[ 8064.059049] Hardware name: Generic DRA74X (Flattened Device Tree)
[ 8064.065166] task: d2689e00 ti: ecf36000 task.ti: ecf36000
[ 8064.070596] PC is at __get_page_tail+0x1c/0x138
[ 8064.075185] LR is at gckOS_MapUserMemory+0x804/0xac8 [galcore]
[ 8064.081043] pc : [<c00e1950>]    lr : [<bf532348>]    psr: 200f0013
[ 8064.081043] sp : ecf37c80  ip : ecf37c98  fp : ecf37c94
[ 8064.092568] r10: c0718904  r9 : ae489000  r8 : c078b8c0
[ 8064.097813] r7 : ee49e000  r6 : 00000000  r5 : ffeee448  r4 : ee6c78b8
[ 8064.104366] r3 : ffffc538  r2 : 00000000  r1 : 00080000  r0 : ee49e000
[ 8064.110920] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[ 8064.118084] Control: 30c5387d  Table: acd29180  DAC: 55555555
[ 8064.123854] Process Thread (pooled) (pid: 7282, stack limit = 0xecf36210)
[ 8064.130669] Stack: (0xecf37c80 to 0xecf38000)
[ 8064.135045] 7c80: ee6c78b8 ffeee448 ecf37d24 ecf37c98 bf532348 c00e1940 00000001 00000000
[ 8064.143258] 7ca0: eea50800 00000000 c00a4b98 eea507fc ae489000 ffffe000 ffeee000 eea50800
[ 8064.151471] 7cc0: 000005e4 00000179 00000000 ecd29140 fffffff2 ae489000 ffffffff eea50800
[ 8064.159684] 7ce0: 00000177 ed2a4000 00003548 00000000 ffffffff 00000000 ffffe000 00000000
[ 8064.167895] 7d00: ecf37db0 ed2a4e00 00000001 ffffffff 00000000 00000000 ecf37d84 ecf37d28
[ 8064.176107] 7d20: bf539c98 bf531b50 00177000 ecf37d44 ecf37dec c9177840 00000000 ecf37d48
[ 8064.184319] 7d40: 00000000 00000000 00000000 00001c55 c456f8e8 b2f1d000 ffffffff 00000000
[ 8064.192530] 7d60: ecf36000 ee04be00 c5ab1680 00007530 ecf37d90 ecf36000 ecf37f14 ecf37d88
[ 8064.200741] 7d80: bf536428 bf5390f0 ecf37e0c ecf37d98 ae286a10 00000000 00000140 00000000
[ 8064.208952] 7da0: ae286a10 00000000 00000140 00000000 0000000b 00000002 02b9606c b6de3f8e
[ 8064.217164] 7dc0: 00000028 b6de2894 b6f56ce8 b6f444a4 ae489000 00000000 ffffffff 00000000
[ 8064.225377] 7de0: 00177000 00000000 00000000 00000000 ae286a98 572c0d98 00000000 00000000
[ 8064.233588] 7e00: ae286a98 b6de3f8e ae286ab8 ae286ac0 ae286b2c b6f360e9 ae286ac0 b6f57ab4
[ 8064.241801] 7e20: 00000007 00000000 00000005 00000000 00000001 b6f50810 b609c41c b6f4c000
[ 8064.250013] 7e40: ae286c4c ae286d00 00000000 b6f509c8 b6f50810 b6f509c8 079105f9 b2f00010
[ 8064.258224] 7e60: b6de2894 b6f50810 000247b8 b2f75848 b2f19df0 ae286c58 ae489000 b6224f27
[ 8064.266435] 7e80: 00000001 00000000 b2f303d8 b60ae000 00000000 000001e3 00000004 b6e01b3b
[ 8064.274646] 7ea0: ae287890 b6e1e69c 00000001 ae286c58 ae489000 00000000 00000002 00000001
[ 8064.282858] 7ec0: 00000006 00000132 b2f078ec b6e1e69c ae286b4c b6e01dfd b2f078f0 00000001
[ 8064.291070] 7ee0: b2f078d8 00000000 ae286c58 b2f19dcc ae2869c8 edc21100 ee9bce40 00000009
[ 8064.299283] 7f00: ae2869c8 ecf36000 ecf37f7c ecf37f18 c0134e00 bf536314 00021000 00000003
[ 8064.307494] 7f20: ee9bce40 00004000 ecf37f5c ecf37f38 c013f000 c00860fc 00002710 00000009
[ 8064.315706] 7f40: 00007530 00007530 ae2869c8 ecf36000 ecf37f6c ee9bce41 00000009 ee9bce40
[ 8064.323918] 7f60: 00007530 ae2869c8 ecf36000 00000000 ecf37fa4 ecf37f80 c0135060 c0134a1c
[ 8064.332129] 7f80: 00002710 b6e28b3c 00007530 00000036 c000fbc4 ecf36000 00000000 ecf37fa8
[ 8064.340341] 7fa0: c000fa20 c0135030 00002710 b6e28b3c 00000009 00007530 ae2869c8 b2f02d70
[ 8064.348553] 7fc0: 00002710 b6e28b3c 00007530 00000036 00000140 00003c00 00000320 00000004
[ 8064.356765] 7fe0: b6e1e808 ae2869b4 b6e0a67b b625f4d6 200f0030 00000009 6913410e 61400b00
[ 8064.364973] Backtrace:
[ 8064.367471] [<c00e1934>] (__get_page_tail) from [<bf532348>] (gckOS_MapUserMemory+0x804/0xac8 [galcore])
[ 8064.376990]  r5:ffeee448 r4:ee6c78b8
[ 8064.380654] [<bf531b44>] (gckOS_MapUserMemory [galcore]) from [<bf539c98>] (gckKERNEL_Dispatch+0xbb4/0x11ac [galcore])
[ 8064.391393]  r10:00000000 r9:00000000 r8:ffffffff r7:00000001 r6:ed2a4e00 r5:ecf37db0
[ 8064.399299]  r4:00000000
[ 8064.401908] [<bf5390e4>] (gckKERNEL_Dispatch [galcore]) from [<bf536428>] (drv_ioctl+0x120/0x28c [galcore])
[ 8064.411689]  r9:ecf36000 r8:ecf37d90 r7:00007530 r6:c5ab1680 r5:ee04be00 r4:ecf36000
[ 8064.419540] [<bf536308>] (drv_ioctl [galcore]) from [<c0134e00>] (do_vfs_ioctl+0x3f0/0x614)
[ 8064.427925]  r9:ecf36000 r8:ae2869c8 r7:00000009 r6:ee9bce40 r5:edc21100 r4:ae2869c8
[ 8064.435748] [<c0134a10>] (do_vfs_ioctl) from [<c0135060>] (SyS_ioctl+0x3c/0x64)
[ 8064.443084]  r10:00000000 r9:ecf36000 r8:ae2869c8 r7:00007530 r6:ee9bce40 r5:00000009
[ 8064.450989]  r4:ee9bce41
[ 8064.453546] [<c0135024>] (SyS_ioctl) from [<c000fa20>] (ret_fast_syscall+0x0/0x34)
[ 8064.461146]  r9:ecf36000 r8:c000fbc4 r7:00000036 r6:00007530 r5:b6e28b3c r4:00002710
[ 8064.468967] Code: e5903014 e3130001 12433001 01a03000 (e5932004)
[ 8064.475171] ---[ end trace b26cc92b34d64366 ]---

How can I get rid of the memcpy in my code? Thanks.