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Fri, 16 Oct 2020 12:08:55 +0200 (CEST) Date: Fri, 16 Oct 2020 12:08:54 +0200 From: Sam Ravnborg To: Thomas Zimmermann Cc: maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@linux.ie, daniel@ffwll.ch, 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 v4 09/10] dma-buf-map: Add memcpy and pointer-increment interfaces Message-ID: <20201016100854.GA1042954@ravnborg.org> References: <20201015123806.32416-1-tzimmermann@suse.de> <20201015123806.32416-10-tzimmermann@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201015123806.32416-10-tzimmermann@suse.de> X-CMAE-Score: 0 X-CMAE-Analysis: v=2.3 cv=S433PrkP c=1 sm=1 tr=0 a=S6zTFyMACwkrwXSdXUNehg==:117 a=S6zTFyMACwkrwXSdXUNehg==:17 a=kj9zAlcOel0A:10 a=7gkXJVJtAAAA:8 a=0A2xud3A4b7FAmx5SMIA:9 a=7a1rlSNJFqSX5uOf:21 a=OU_kl8OV53ZSq-ss:21 a=CjuIK1q_8ugA:10 a=E9Po1WZjFZOl8hwRPBS3:22 Hi Thomas. On Thu, Oct 15, 2020 at 02:38:05PM +0200, Thomas Zimmermann wrote: > To do framebuffer updates, one needs memcpy from system memory and a > pointer-increment function. Add both interfaces with documentation. > > Signed-off-by: Thomas Zimmermann Looks good. Reviewed-by: Sam Ravnborg > --- > include/linux/dma-buf-map.h | 72 +++++++++++++++++++++++++++++++------ > 1 file changed, 62 insertions(+), 10 deletions(-) > > diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h > index 2e8bbecb5091..6ca0f304dda2 100644 > --- a/include/linux/dma-buf-map.h > +++ b/include/linux/dma-buf-map.h > @@ -32,6 +32,14 @@ > * accessing the buffer. Use the returned instance and the helper functions > * to access the buffer's memory in the correct way. > * > + * The type :c:type:`struct dma_buf_map ` and its helpers are > + * actually independent from the dma-buf infrastructure. When sharing buffers > + * among devices, drivers have to know the location of the memory to access > + * the buffers in a safe way. :c:type:`struct dma_buf_map ` > + * solves this problem for dma-buf and its users. If other drivers or > + * sub-systems require similar functionality, the type could be generalized > + * and moved to a more prominent header file. > + * > * Open-coding access to :c:type:`struct dma_buf_map ` is > * considered bad style. Rather then accessing its fields directly, use one > * of the provided helper functions, or implement your own. For example, > @@ -51,6 +59,14 @@ > * > * dma_buf_map_set_vaddr_iomem(&map. 0xdeadbeaf); > * > + * Instances of struct dma_buf_map do not have to be cleaned up, but > + * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings > + * always refer to system memory. > + * > + * .. code-block:: c > + * > + * dma_buf_map_clear(&map); > + * > * Test if a mapping is valid with either dma_buf_map_is_set() or > * dma_buf_map_is_null(). > * > @@ -73,17 +89,19 @@ > * if (dma_buf_map_is_equal(&sys_map, &io_map)) > * // always false > * > - * Instances of struct dma_buf_map do not have to be cleaned up, but > - * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings > - * always refer to system memory. > + * A set up instance of struct dma_buf_map can be used to access or manipulate > + * the buffer memory. Depending on the location of the memory, the provided > + * helpers will pick the correct operations. Data can be copied into the memory > + * with dma_buf_map_memcpy_to(). The address can be manipulated with > + * dma_buf_map_incr(). > * > - * The type :c:type:`struct dma_buf_map ` and its helpers are > - * actually independent from the dma-buf infrastructure. When sharing buffers > - * among devices, drivers have to know the location of the memory to access > - * the buffers in a safe way. :c:type:`struct dma_buf_map ` > - * solves this problem for dma-buf and its users. If other drivers or > - * sub-systems require similar functionality, the type could be generalized > - * and moved to a more prominent header file. > + * .. code-block:: c > + * > + * const void *src = ...; // source buffer > + * size_t len = ...; // length of src > + * > + * dma_buf_map_memcpy_to(&map, src, len); > + * dma_buf_map_incr(&map, len); // go to first byte after the memcpy > */ > > /** > @@ -210,4 +228,38 @@ static inline void dma_buf_map_clear(struct dma_buf_map *map) > } > } > > +/** > + * dma_buf_map_memcpy_to - Memcpy into dma-buf mapping > + * @dst: The dma-buf mapping structure > + * @src: The source buffer > + * @len: The number of byte in src > + * > + * Copies data into a dma-buf mapping. The source buffer is in system > + * memory. Depending on the buffer's location, the helper picks the correct > + * method of accessing the memory. > + */ > +static inline void dma_buf_map_memcpy_to(struct dma_buf_map *dst, const void *src, size_t len) > +{ > + if (dst->is_iomem) > + memcpy_toio(dst->vaddr_iomem, src, len); > + else > + memcpy(dst->vaddr, src, len); > +} > + > +/** > + * dma_buf_map_incr - Increments the address stored in a dma-buf mapping > + * @map: The dma-buf mapping structure > + * @incr: The number of bytes to increment > + * > + * Increments the address stored in a dma-buf mapping. Depending on the > + * buffer's location, the correct value will be updated. > + */ > +static inline void dma_buf_map_incr(struct dma_buf_map *map, size_t incr) > +{ > + if (map->is_iomem) > + map->vaddr_iomem += incr; > + else > + map->vaddr += incr; > +} > + > #endif /* __DMA_BUF_MAP_H__ */ > -- > 2.28.0