On 06/12/2012 09:34 AM, Nellutla, Aditya wrote:
> Florian,
>
> I didn't receive any review comments for the patch below. So could you please merge the patch?
As far as I can see there is no feasible alternative so I applied this
patch. If anyone happens to have problems with the larger memory
requirements caused by this, I guess we could make this behavior depend
on a Kconfig symbol.
Best regards,
Florian Tobias Schandinat
>
> Regards,
> Aditya
>
> -----Original Message-----
> From: Nellutla, Aditya
> Sent: Monday, June 04, 2012 11:33 AM
> To: Nellutla, Aditya; linux-fbdev@xxxxxxxxxxxxxxx
> Cc: Hiremath, Vaibhav
> Subject: RE: [PATCH] da8xx-fb: Rounding FB size to satisfy SGX buffer requirements
>
> All,
> Did you get chance to review this patch? Request to give your feedback as early as possible.
>
> Regards,
> Aditya
>
> -----Original Message-----
> From: Nellutla, Aditya
> Sent: Wednesday, May 23, 2012 11:37 AM
> To: linux-fbdev@xxxxxxxxxxxxxxx
> Cc: Nellutla, Aditya
> Subject: [PATCH] da8xx-fb: Rounding FB size to satisfy SGX buffer requirements
>
> In the real time use-case when SGX is used for rendering to FB buffers it has been
> observed that, the available memory from framebuffer driver is not sufficient for
> SGX under certain cases (like 16-bit WVGA resolution). SGX requires 2 swap buffers
> with each of the buffers aligned to lcm(line_length, PAGE_SIZE).
>
> Inorder to satisfy this requirement, we have two options,
>
> - Increase number of FB buffers (LCD_NUM_BUFFERS) to 3. This is not
> recommended as we end up wasting huge memory in most of the cases.
>
> - Align FB buffers to lcm(line_length, PAGE_SIZE).This ensures framebuffer
> size is increased to satisfy SGX requirements keeping alignment intact.
>
> This patch makes sure that FB allocates buffers aligned to above formula.
>
> Signed-off-by: Aditya Nellutla <aditya.n@xxxxxx>
> ---
> drivers/video/da8xx-fb.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/video/da8xx-fb.c b/drivers/video/da8xx-fb.c
> index 47118c7..2f24c19 100644
> --- a/drivers/video/da8xx-fb.c
> +++ b/drivers/video/da8xx-fb.c
> @@ -31,6 +31,7 @@
> #include <linux/cpufreq.h>
> #include <linux/console.h>
> #include <linux/slab.h>
> +#include <linux/lcm.h>
> #include <video/da8xx-fb.h>
> #include <asm/div64.h>
>
> @@ -1114,6 +1115,7 @@ static int __devinit fb_probe(struct platform_device *device)
> struct da8xx_fb_par *par;
> resource_size_t len;
> int ret, i;
> + unsigned long ulcm;
>
> if (fb_pdata == NULL) {
> dev_err(&device->dev, "Can not get platform data\n");
> @@ -1209,7 +1211,8 @@ static int __devinit fb_probe(struct platform_device *device)
>
> /* allocate frame buffer */
> par->vram_size = lcdc_info->width * lcdc_info->height * lcd_cfg->bpp;
> - par->vram_size = PAGE_ALIGN(par->vram_size/8);
> + ulcm = lcm((lcdc_info->width * lcd_cfg->bpp)/8, PAGE_SIZE);
> + par->vram_size = roundup(par->vram_size/8, ulcm);
> par->vram_size = par->vram_size * LCD_NUM_BUFFERS;
>
> par->vram_virt = dma_alloc_coherent(NULL,
--
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