[PATCH 1/5] [media] rockchip/rga: v4l2 m2m support
jacobchen110 at gmail.com
Tue Jun 27 17:29:09 PDT 2017
2017-06-27 16:39 GMT+08:00 Tomasz Figa <tfiga at chromium.org>:
> Hi Jacob,
> Please see my comments inline.
> On Mon, Jun 26, 2017 at 11:51 PM, Jacob Chen <jacob-chen at iotwrt.com> wrote:
>> Rockchip RGA is a separate 2D raster graphic acceleration unit. It
>> accelerates 2D graphics operations, such as point/line drawing, image
>> scaling, rotation, BitBLT, alpha blending and image blur/sharpness.
>> +static int rga_buf_init(struct vb2_buffer *vb)
>> + struct rga_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
>> + struct rockchip_rga *rga = ctx->rga;
>> + struct sg_table *sgt;
>> + struct scatterlist *sgl;
>> + unsigned int *pages;
>> + struct rga_buf *buf;
>> + unsigned int address, len, i, p;
>> + unsigned int mapped_size = 0;
>> + /* Create local MMU table for RGA */
>> + sgt = vb2_plane_cookie(vb, 0);
>> + /*
>> + * Alloc (2^3 * 4K) = 32K byte for storing pages, those space could
>> + * cover 32K * 4K = 128M ram address.
> Unless I'm missing something, there is 1024 32-bit values in one 4K
> page, which can point to 4 MB of memory. The code allocates 8 of them,
> which in total allows at most 32 MB per buffer.
>> + */
>> + pages = (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3);
> This is rather unfortunate and you should expect failures here on
> actively used systems with uptime longer than few hours. Changing this
> to dma_alloc_coherent() and enabling CMA _might_ give you a bit better
> success rate, but...
I decide to alloc a page pool when driver probe and get page from that poll.
> Normally, this kind of (scatter-gather capable) hardware would allow
> some kind of linking of separate pages, e.g. last entry in the page
> would point to the next page, or something like that. Doesn't this RGA
> block have something similar?
> Best regards,
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