On 07/06/16 15:43, Daniel Vetter wrote: > On Tue, Jun 07, 2016 at 01:18:09PM +0100, Robin Murphy wrote: >> In the absence of an fb_mmap callback, the fbdev code falls back to a >> naive implementation which relies upon the DMA address being the same >> as the physical address, and the buffer being physically contiguous >> from there. Whilst this often holds for standard CMA allocations via >> the platform's regular DMA ops, if the allocation is provided by an >> IOMMU then such assumptions can fall apart spectacularly. >> >> To resolve this, reroute the fb_mmap call to the appropriate DMA API >> implementation, as per the other cma_helper calls. >> >> Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch> >> Signed-off-by: Robin Murphy <robin.murphy at arm.com> >> --- >> >> Resending rebased to 4.7-rc1 with Daniel's ack. I know Russell raised >> some concerns about the general way fb_cma_helper uses fb_info[1], but >> AFAICS that's a longstanding separate problem orthogonal to this patch. > > Do you want me to pull this in through drm-misc, or will this land through > some driver tree? Note that I'll do -misc pulls about every week, so if > you don't send your pull this week I'd like to pull it in to avoid > hilarity^W needless conflicts.
Yeah, drm-misc sounds appropriate so if you're happy to pick it up, please feel free :) Robin. > -Daniel > >> >> Robin. >> >> [1]:http://thread.gmane.org/gmane.comp.video.dri.devel/149288 >> >> drivers/gpu/drm/drm_fb_cma_helper.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c >> b/drivers/gpu/drm/drm_fb_cma_helper.c >> index 172cafe11c71..a25afc068d3f 100644 >> --- a/drivers/gpu/drm/drm_fb_cma_helper.c >> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c >> @@ -23,6 +23,7 @@ >> #include <drm/drm_crtc_helper.h> >> #include <drm/drm_gem_cma_helper.h> >> #include <drm/drm_fb_cma_helper.h> >> +#include <linux/dma-mapping.h> >> #include <linux/module.h> >> >> #define DEFAULT_FBDEFIO_DELAY_MS 50 >> @@ -297,6 +298,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void >> *arg) >> EXPORT_SYMBOL_GPL(drm_fb_cma_debugfs_show); >> #endif >> >> +static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma) >> +{ >> + return dma_mmap_writecombine(info->device, vma, info->screen_base, >> + info->fix.smem_start, info->fix.smem_len); >> +} >> + >> static struct fb_ops drm_fbdev_cma_ops = { >> .owner = THIS_MODULE, >> .fb_fillrect = drm_fb_helper_sys_fillrect, >> @@ -307,6 +314,7 @@ static struct fb_ops drm_fbdev_cma_ops = { >> .fb_blank = drm_fb_helper_blank, >> .fb_pan_display = drm_fb_helper_pan_display, >> .fb_setcmap = drm_fb_helper_setcmap, >> + .fb_mmap = drm_fb_cma_mmap, >> }; >> >> static int drm_fbdev_cma_deferred_io_mmap(struct fb_info *info, >> -- >> 2.8.1.dirty >> >
