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Thu, 22 Oct 2020 01:05:38 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id 32sm2105875wro.31.2020.10.22.01.05.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Oct 2020 01:05:37 -0700 (PDT) Date: Thu, 22 Oct 2020 10:05:34 +0200 From: Daniel Vetter To: Thomas Zimmermann Cc: maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@linux.ie, daniel@ffwll.ch, sam@ravnborg.org, alexander.deucher@amd.com, christian.koenig@amd.com, kraxel@redhat.com, l.stach@pengutronix.de, linux+etnaviv@armlinux.org.uk, christian.gmeiner@gmail.com, inki.dae@samsung.com, jy0922.shim@samsung.com, sw0312.kim@samsung.com, kyungmin.park@samsung.com, kgene@kernel.org, krzk@kernel.org, yuq825@gmail.com, bskeggs@redhat.com, robh@kernel.org, tomeu.vizoso@collabora.com, steven.price@arm.com, alyssa.rosenzweig@collabora.com, hjc@rock-chips.com, heiko@sntech.de, hdegoede@redhat.com, sean@poorly.run, eric@anholt.net, oleksandr_andrushchenko@epam.com, ray.huang@amd.com, sumit.semwal@linaro.org, emil.velikov@collabora.com, luben.tuikov@amd.com, apaneers@amd.com, linus.walleij@linaro.org, melissa.srw@gmail.com, chris@chris-wilson.co.uk, miaoqinglang@huawei.com, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, virtualization@lists.linux-foundation.org, etnaviv@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, lima@lists.freedesktop.org, nouveau@lists.freedesktop.org, spice-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, xen-devel@lists.xenproject.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Subject: Re: [PATCH v5 10/10] drm/fb_helper: Support framebuffers in I/O memory Message-ID: <20201022080534.GT401619@phenom.ffwll.local> References: <20201020122046.31167-1-tzimmermann@suse.de> <20201020122046.31167-11-tzimmermann@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201020122046.31167-11-tzimmermann@suse.de> X-Operating-System: Linux phenom 5.7.0-1-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Tue, Oct 20, 2020 at 02:20:46PM +0200, Thomas Zimmermann wrote: > At least sparc64 requires I/O-specific access to framebuffers. This > patch updates the fbdev console accordingly. > > For drivers with direct access to the framebuffer memory, the callback > functions in struct fb_ops test for the type of memory and call the rsp > fb_sys_ of fb_cfb_ functions. Read and write operations are implemented > internally by DRM's fbdev helper. > > For drivers that employ a shadow buffer, fbdev's blit function retrieves > the framebuffer address as struct dma_buf_map, and uses dma_buf_map > interfaces to access the buffer. > > The bochs driver on sparc64 uses a workaround to flag the framebuffer as > I/O memory and avoid a HW exception. With the introduction of struct > dma_buf_map, this is not required any longer. The patch removes the rsp > code from both, bochs and fbdev. > > v5: > * implement fb_read/fb_write internally (Daniel, Sam) > v4: > * move dma_buf_map changes into separate patch (Daniel) > * TODO list: comment on fbdev updates (Daniel) > > Signed-off-by: Thomas Zimmermann > Tested-by: Sam Ravnborg > --- > Documentation/gpu/todo.rst | 19 ++- > drivers/gpu/drm/bochs/bochs_kms.c | 1 - > drivers/gpu/drm/drm_fb_helper.c | 227 ++++++++++++++++++++++++++++-- > include/drm/drm_mode_config.h | 12 -- > 4 files changed, 230 insertions(+), 29 deletions(-) > > diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst > index 7e6fc3c04add..638b7f704339 100644 > --- a/Documentation/gpu/todo.rst > +++ b/Documentation/gpu/todo.rst > @@ -197,13 +197,28 @@ Convert drivers to use drm_fbdev_generic_setup() > ------------------------------------------------ > > Most drivers can use drm_fbdev_generic_setup(). Driver have to implement > -atomic modesetting and GEM vmap support. Current generic fbdev emulation > -expects the framebuffer in system memory (or system-like memory). > +atomic modesetting and GEM vmap support. Historically, generic fbdev emulation > +expected the framebuffer in system memory or system-like memory. By employing > +struct dma_buf_map, drivers with frambuffers in I/O memory can be supported > +as well. > > Contact: Maintainer of the driver you plan to convert > > Level: Intermediate > > +Reimplement functions in drm_fbdev_fb_ops without fbdev > +------------------------------------------------------- > + > +A number of callback functions in drm_fbdev_fb_ops could benefit from > +being rewritten without dependencies on the fbdev module. Some of the > +helpers could further benefit from using struct dma_buf_map instead of > +raw pointers. > + > +Contact: Thomas Zimmermann , Daniel Vetter > + > +Level: Advanced > + > + > drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup > ----------------------------------------------------------------- > > diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c > index 13d0d04c4457..853081d186d5 100644 > --- a/drivers/gpu/drm/bochs/bochs_kms.c > +++ b/drivers/gpu/drm/bochs/bochs_kms.c > @@ -151,7 +151,6 @@ int bochs_kms_init(struct bochs_device *bochs) > bochs->dev->mode_config.preferred_depth = 24; > bochs->dev->mode_config.prefer_shadow = 0; > bochs->dev->mode_config.prefer_shadow_fbdev = 1; > - bochs->dev->mode_config.fbdev_use_iomem = true; > bochs->dev->mode_config.quirk_addfb_prefer_host_byte_order = true; > > bochs->dev->mode_config.funcs = &bochs_mode_funcs; > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > index 6212cd7cde1d..1d3180841778 100644 > --- a/drivers/gpu/drm/drm_fb_helper.c > +++ b/drivers/gpu/drm/drm_fb_helper.c > @@ -372,24 +372,22 @@ static void drm_fb_helper_resume_worker(struct work_struct *work) > } > > static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper, > - struct drm_clip_rect *clip) > + struct drm_clip_rect *clip, > + struct dma_buf_map *dst) > { > struct drm_framebuffer *fb = fb_helper->fb; > unsigned int cpp = fb->format->cpp[0]; > size_t offset = clip->y1 * fb->pitches[0] + clip->x1 * cpp; > void *src = fb_helper->fbdev->screen_buffer + offset; > - void *dst = fb_helper->buffer->map.vaddr + offset; > size_t len = (clip->x2 - clip->x1) * cpp; > unsigned int y; > > - for (y = clip->y1; y < clip->y2; y++) { > - if (!fb_helper->dev->mode_config.fbdev_use_iomem) > - memcpy(dst, src, len); > - else > - memcpy_toio((void __iomem *)dst, src, len); > + dma_buf_map_incr(dst, offset); /* go to first pixel within clip rect */ > > + for (y = clip->y1; y < clip->y2; y++) { > + dma_buf_map_memcpy_to(dst, src, len); > + dma_buf_map_incr(dst, fb->pitches[0]); > src += fb->pitches[0]; > - dst += fb->pitches[0]; > } > } > > @@ -417,8 +415,9 @@ static void drm_fb_helper_dirty_work(struct work_struct *work) > ret = drm_client_buffer_vmap(helper->buffer, &map); > if (ret) > return; > - drm_fb_helper_dirty_blit_real(helper, &clip_copy); > + drm_fb_helper_dirty_blit_real(helper, &clip_copy, &map); > } > + > if (helper->fb->funcs->dirty) > helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, > &clip_copy, 1); > @@ -2027,6 +2026,206 @@ static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma) > return -ENODEV; > } > > +static bool drm_fbdev_use_iomem(struct fb_info *info) > +{ > + struct drm_fb_helper *fb_helper = info->par; > + struct drm_client_buffer *buffer = fb_helper->buffer; > + > + return !drm_fbdev_use_shadow_fb(fb_helper) && buffer->map.is_iomem; > +} > + > +static ssize_t fb_read_screen_base(struct fb_info *info, char __user *buf, size_t count, > + loff_t pos) > +{ > + const char __iomem *src = info->screen_base + pos; Maybe a bit much a bikeshed, but I'd write this in terms of drm objects, like the dirty_blit function, using the dma_buf_map (instead of the fb_info parameter). And then instead of screen_base and screen_buffer suffixes give them _mem and _iomem suffixes. Same for write below. Or I'm not quite understanding why we do it like this here - I don't think this code will be used outside of the generic fbdev code, so we can always assume that drm_fb_helper->buffer is set up. The other thing I think we need is some minimal testcases to make sure. The fbtest tool used way back seems to have disappeared, I couldn't find a copy of the source anywhere anymore. With all that: Acked-by: Daniel Vetter Cheers, Daniel > + size_t alloc_size = min(count, PAGE_SIZE); > + ssize_t ret = 0; > + char *tmp; > + > + tmp = kmalloc(alloc_size, GFP_KERNEL); > + if (!tmp) > + return -ENOMEM; > + > + while (count) { > + size_t c = min(count, alloc_size); > + > + memcpy_fromio(tmp, src, c); > + if (copy_to_user(buf, tmp, c)) { > + ret = -EFAULT; > + break; > + } > + > + src += c; > + buf += c; > + ret += c; > + count -= c; > + } > + > + kfree(tmp); > + > + return ret; > +} > + > +static ssize_t fb_read_screen_buffer(struct fb_info *info, char __user *buf, size_t count, > + loff_t pos) > +{ > + const char *src = info->screen_buffer + pos; > + > + if (copy_to_user(buf, src, count)) > + return -EFAULT; > + > + return count; > +} > + > +static ssize_t drm_fbdev_fb_read(struct fb_info *info, char __user *buf, > + size_t count, loff_t *ppos) > +{ > + loff_t pos = *ppos; > + size_t total_size; > + ssize_t ret; > + > + if (info->state != FBINFO_STATE_RUNNING) > + return -EPERM; > + > + if (info->screen_size) > + total_size = info->screen_size; > + else > + total_size = info->fix.smem_len; > + > + if (pos >= total_size) > + return 0; > + if (count >= total_size) > + count = total_size; > + if (total_size - count < pos) > + count = total_size - pos; > + > + if (drm_fbdev_use_iomem(info)) > + ret = fb_read_screen_base(info, buf, count, pos); > + else > + ret = fb_read_screen_buffer(info, buf, count, pos); > + > + if (ret > 0) > + *ppos = ret; > + > + return ret; > +} > + > +static ssize_t fb_write_screen_base(struct fb_info *info, const char __user *buf, size_t count, > + loff_t pos) > +{ > + char __iomem *dst = info->screen_base + pos; > + size_t alloc_size = min(count, PAGE_SIZE); > + ssize_t ret = 0; > + u8 *tmp; > + > + tmp = kmalloc(alloc_size, GFP_KERNEL); > + if (!tmp) > + return -ENOMEM; > + > + while (count) { > + size_t c = min(count, alloc_size); > + > + if (copy_from_user(tmp, buf, c)) { > + ret = -EFAULT; > + break; > + } > + memcpy_toio(dst, tmp, c); > + > + dst += c; > + buf += c; > + ret += c; > + count -= c; > + } > + > + kfree(tmp); > + > + return ret; > +} > + > +static ssize_t fb_write_screen_buffer(struct fb_info *info, const char __user *buf, size_t count, > + loff_t pos) > +{ > + char *dst = info->screen_buffer + pos; > + > + if (copy_from_user(dst, buf, count)) > + return -EFAULT; > + > + return count; > +} > + > +static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf, > + size_t count, loff_t *ppos) > +{ > + loff_t pos = *ppos; > + size_t total_size; > + ssize_t ret; > + int err; > + > + if (info->state != FBINFO_STATE_RUNNING) > + return -EPERM; > + > + if (info->screen_size) > + total_size = info->screen_size; > + else > + total_size = info->fix.smem_len; > + > + if (pos > total_size) > + return -EFBIG; > + if (count > total_size) { > + err = -EFBIG; > + count = total_size; > + } > + if (total_size - count < pos) { > + if (!err) > + err = -ENOSPC; > + count = total_size - pos; > + } > + > + /* > + * Copy to framebuffer even if we already logged an error. Emulates > + * the behavior of the original fbdev implementation. > + */ > + if (drm_fbdev_use_iomem(info)) > + ret = fb_write_screen_base(info, buf, count, pos); > + else > + ret = fb_write_screen_buffer(info, buf, count, pos); > + > + if (ret > 0) > + *ppos = ret; > + > + if (err) > + return err; > + > + return ret; > +} > + > +static void drm_fbdev_fb_fillrect(struct fb_info *info, > + const struct fb_fillrect *rect) > +{ > + if (drm_fbdev_use_iomem(info)) > + drm_fb_helper_cfb_fillrect(info, rect); > + else > + drm_fb_helper_sys_fillrect(info, rect); > +} > + > +static void drm_fbdev_fb_copyarea(struct fb_info *info, > + const struct fb_copyarea *area) > +{ > + if (drm_fbdev_use_iomem(info)) > + drm_fb_helper_cfb_copyarea(info, area); > + else > + drm_fb_helper_sys_copyarea(info, area); > +} > + > +static void drm_fbdev_fb_imageblit(struct fb_info *info, > + const struct fb_image *image) > +{ > + if (drm_fbdev_use_iomem(info)) > + drm_fb_helper_cfb_imageblit(info, image); > + else > + drm_fb_helper_sys_imageblit(info, image); > +} > + > static const struct fb_ops drm_fbdev_fb_ops = { > .owner = THIS_MODULE, > DRM_FB_HELPER_DEFAULT_OPS, > @@ -2034,11 +2233,11 @@ static const struct fb_ops drm_fbdev_fb_ops = { > .fb_release = drm_fbdev_fb_release, > .fb_destroy = drm_fbdev_fb_destroy, > .fb_mmap = drm_fbdev_fb_mmap, > - .fb_read = drm_fb_helper_sys_read, > - .fb_write = drm_fb_helper_sys_write, > - .fb_fillrect = drm_fb_helper_sys_fillrect, > - .fb_copyarea = drm_fb_helper_sys_copyarea, > - .fb_imageblit = drm_fb_helper_sys_imageblit, > + .fb_read = drm_fbdev_fb_read, > + .fb_write = drm_fbdev_fb_write, > + .fb_fillrect = drm_fbdev_fb_fillrect, > + .fb_copyarea = drm_fbdev_fb_copyarea, > + .fb_imageblit = drm_fbdev_fb_imageblit, > }; > > static struct fb_deferred_io drm_fbdev_defio = { > diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h > index 5ffbb4ed5b35..ab424ddd7665 100644 > --- a/include/drm/drm_mode_config.h > +++ b/include/drm/drm_mode_config.h > @@ -877,18 +877,6 @@ struct drm_mode_config { > */ > bool prefer_shadow_fbdev; > > - /** > - * @fbdev_use_iomem: > - * > - * Set to true if framebuffer reside in iomem. > - * When set to true memcpy_toio() is used when copying the framebuffer in > - * drm_fb_helper.drm_fb_helper_dirty_blit_real(). > - * > - * FIXME: This should be replaced with a per-mapping is_iomem > - * flag (like ttm does), and then used everywhere in fbdev code. > - */ > - bool fbdev_use_iomem; > - > /** > * @quirk_addfb_prefer_xbgr_30bpp: > * > -- > 2.28.0 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch