[PATCH] drm/exynos: Add check for IOMMU while passing physically continous memory flag

[Sachin Kamat]

Hi Vikas,

On 2 August 2013 09:23, Vikas Sajjan <vikas.sajjan at linaro.org> wrote:
> Hi Tomasz,
>
>
> On 2 August 2013 04:50, Tomasz Figa <tomasz.figa at gmail.com> wrote:
>>
>> Hi Vikas,
>>
>> On Thursday 01 of August 2013 16:49:32 Vikas Sajjan wrote:
>> > While trying to get boot-logo up on exynos5420 SMDK which has eDP panel
>> > connected with resolution 2560x1600, following error occured even with
>> > IOMMU enabled:
>> > [0.880000] [drm:lowlevel_buffer_allocate] *ERROR* failed to allocate
>> > buffer. [0.890000] [drm] Initialized exynos 1.0.0 20110530 on minor 0
>> >
>> > This patch fixes the issue by adding a check for IOMMU.
>> >
>> > Signed-off-by: Vikas Sajjan <vikas.sajjan at linaro.org>
>> > Signed-off-by: Arun Kumar <arun.kk at samsung.com>
>> > ---
>> >  drivers/gpu/drm/exynos/exynos_drm_fbdev.c |    9 ++++++++-
>> >  1 file changed, 8 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
>> > b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c index 8e60bd6..2a86666
>> > 100644
>> > --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
>> > +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
>> > @@ -16,6 +16,7 @@
>> >  #include <drm/drm_crtc.h>
>> >  #include <drm/drm_fb_helper.h>
>> >  #include <drm/drm_crtc_helper.h>
>> > +#include <drm/exynos_drm.h>
>> >
>> >  #include "exynos_drm_drv.h"
>> >  #include "exynos_drm_fb.h"
>> > @@ -143,6 +144,7 @@ static int exynos_drm_fbdev_create(struct
>> > drm_fb_helper *helper, struct platform_device *pdev = dev->platformdev;
>> >       unsigned long size;
>> >       int ret;
>> > +     unsigned int flag;
>> >
>> >       DRM_DEBUG_KMS("surface width(%d), height(%d) and bpp(%d\n",
>> >                       sizes->surface_width, sizes->surface_height,
>> > @@ -166,7 +168,12 @@ static int exynos_drm_fbdev_create(struct
>> > drm_fb_helper *helper, size = mode_cmd.pitches[0] * mode_cmd.height;
>> >
>> >       /* 0 means to allocate physically continuous memory */
>> > -     exynos_gem_obj = exynos_drm_gem_create(dev, 0, size);
>> > +     if (!is_drm_iommu_supported(dev))
>> > +             flag = 0;
>> > +     else
>> > +             flag = EXYNOS_BO_NONCONTIG;
>>
>> While noncontig memory might be used for devices that support IOMMU, there
>> should be no problem with using contig memory for them, so this seems more
>> like masking the original problem rather than tracking it down.
>>
>> Could you check why the allocation fails when requesting contiguous
>> memory?
>>
>
> It is failing if i am giving bigger resolution like 2560x1600, but if
> i try for 1280x780 resolution, it   works fine.
> Looks like arm_dma_alloc() is NOT able to allocate bigger buffer of
> size 2560 * 1600 * 4.

You may need to increase the zoneorder (from current default 11 to say
13) if you need large physically contiguous pages.
However I am not sure if it is recommended.

-- 
With warm regards,
Sachin