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[PATCH] arm: exynos increase CONFIG_CMA_SIZE_MBYTES to 96

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  [PATCH] arm: exynos increase CONFIG_CMA_SIZE_MBYTES to 96 Shuah Khan <shuahkh@osg.samsung.com> - 2017-02-28 04:20 +0100
    Re: [PATCH] arm: exynos increase CONFIG_CMA_SIZE_MBYTES to 96 Javier Martinez Canillas <javier@osg.samsung.com> - 2017-02-28 18:00 +0100
      Re: [PATCH] arm: exynos increase CONFIG_CMA_SIZE_MBYTES to 96 Krzysztof Kozlowski <krzk@kernel.org> - 2017-02-28 18:30 +0100
      Re: [PATCH] arm: exynos increase CONFIG_CMA_SIZE_MBYTES to 96 Shuah Khan <shuahkh@osg.samsung.com> - 2017-02-28 22:00 +0100

#1589141 — [PATCH] arm: exynos increase CONFIG_CMA_SIZE_MBYTES to 96

Current CMA size of 64 Mbytes is right on the edge of being too small
for some display managers.  With the proposed s5p_mfc patch series that
pre-allocate buffers, when display manager starts, it fails to get GEM
buffers.  Increasing the CMA size to 96 solves the problem.

Change CONFIG_CMA_SIZE_MBYTES to 96 in exynos_defconfig to address the
problem.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 arch/arm/configs/exynos_defconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
index 742baf0..2541414 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -53,7 +53,7 @@ CONFIG_RFKILL_REGULATOR=y
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DMA_CMA=y
-CONFIG_CMA_SIZE_MBYTES=64
+CONFIG_CMA_SIZE_MBYTES=96
 CONFIG_BLK_DEV_LOOP=y
 CONFIG_BLK_DEV_CRYPTOLOOP=y
 CONFIG_BLK_DEV_RAM=y
-- 
2.7.4

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#1589624

Hello Shuah,

The subject line isn't consistent with what's used for exynos_defconfig
changes, please use instead:

ARM: exynos_defconfig: Increase CONFIG_CMA_SIZE_MBYTES to 96

On 02/27/2017 09:23 PM, Shuah Khan wrote:
> Current CMA size of 64 Mbytes is right on the edge of being too small
> for some display managers.  With the proposed s5p_mfc patch series that
> pre-allocate buffers, when display manager starts, it fails to get GEM
> buffers.  Increasing the CMA size to 96 solves the problem.
>
> Change CONFIG_CMA_SIZE_MBYTES to 96 in exynos_defconfig to address the
> problem.
>

As you mention, the problem is when a driver pre-allocates a lot of CMA
memory. So instead of mentioning an in-flight patch series, I would make
the commit message more generic. Something along the following lines:

Current CMA size is 64 Mbytes, but this may not be enough if different
drivers need to allocate big memory chunks.

For example, the s5p-mfc driver may need to do a pre-allocation of N MiB
to decode a H.264 1080p video, and there won't be enough CMA memory left
for others drivers, like the exynos-drm driver that may need to allocate
GEM buffers for the display manager.

Increasing the CMA size to 96 MiB should be enough for most use cases.

> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
> Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---

Patch looks good to me though.

Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America

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#1589646

On Tue, Feb 28, 2017 at 09:52:33AM -0700, Shuah Khan wrote:
> On 02/28/2017 09:42 AM, Javier Martinez Canillas wrote:
> > Hello Shuah,
> > 
> > The subject line isn't consistent with what's used for exynos_defconfig
> > changes, please use instead:
> > 
> > ARM: exynos_defconfig: Increase CONFIG_CMA_SIZE_MBYTES to 96
> > 
> 
> oops - I meant o make it exynos_defconfig
> 
> > On 02/27/2017 09:23 PM, Shuah Khan wrote:
> >> Current CMA size of 64 Mbytes is right on the edge of being too small
> >> for some display managers.  With the proposed s5p_mfc patch series that
> >> pre-allocate buffers, when display manager starts, it fails to get GEM
> >> buffers.  Increasing the CMA size to 96 solves the problem.
> >>
> >> Change CONFIG_CMA_SIZE_MBYTES to 96 in exynos_defconfig to address the
> >> problem.
> >>
> > 
> > As you mention, the problem is when a driver pre-allocates a lot of CMA
> > memory. So instead of mentioning an in-flight patch series, I would make
> > the commit message more generic. Something along the following lines:
> 
> I thought about making it generic and decided to mention the problem I am
> seeing, so there is a context to it. Without this patch, some display
> managers will see regression.
> 
> > 
> > Current CMA size is 64 Mbytes, but this may not be enough if different
> > drivers need to allocate big memory chunks.
> > 
> > For example, the s5p-mfc driver may need to do a pre-allocation of N MiB
> > to decode a H.264 1080p video, and there won't be enough CMA memory left
> > for others drivers, like the exynos-drm driver that may need to allocate
> > GEM buffers for the display manager.
> > 
> > Increasing the CMA size to 96 MiB should be enough for most use cases.
> 
> I will add the current problem to throw away section of the patch for more
> information.
> 
> > 
> >> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
> >> Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> >> ---
> > 
> > Patch looks good to me though.
> > 
> > Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
> 
> thanks for the review. I will send v2 with your reviewed by tag

While at it, please put Suggested-by before Sob tag (let's say
chronological order).


Best regards,
Krzysztof

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#1589768

On 02/28/2017 09:42 AM, Javier Martinez Canillas wrote:
> Hello Shuah,
> 
> The subject line isn't consistent with what's used for exynos_defconfig
> changes, please use instead:
> 
> ARM: exynos_defconfig: Increase CONFIG_CMA_SIZE_MBYTES to 96
> 

oops - I meant o make it exynos_defconfig

> On 02/27/2017 09:23 PM, Shuah Khan wrote:
>> Current CMA size of 64 Mbytes is right on the edge of being too small
>> for some display managers.  With the proposed s5p_mfc patch series that
>> pre-allocate buffers, when display manager starts, it fails to get GEM
>> buffers.  Increasing the CMA size to 96 solves the problem.
>>
>> Change CONFIG_CMA_SIZE_MBYTES to 96 in exynos_defconfig to address the
>> problem.
>>
> 
> As you mention, the problem is when a driver pre-allocates a lot of CMA
> memory. So instead of mentioning an in-flight patch series, I would make
> the commit message more generic. Something along the following lines:

I thought about making it generic and decided to mention the problem I am
seeing, so there is a context to it. Without this patch, some display
managers will see regression.

> 
> Current CMA size is 64 Mbytes, but this may not be enough if different
> drivers need to allocate big memory chunks.
> 
> For example, the s5p-mfc driver may need to do a pre-allocation of N MiB
> to decode a H.264 1080p video, and there won't be enough CMA memory left
> for others drivers, like the exynos-drm driver that may need to allocate
> GEM buffers for the display manager.
> 
> Increasing the CMA size to 96 MiB should be enough for most use cases.

I will add the current problem to throw away section of the patch for more
information.

> 
>> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
>> Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
>> ---
> 
> Patch looks good to me though.
> 
> Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>

thanks for the review. I will send v2 with your reviewed by tag
> 
> Best regards,
> 

-- Shuah

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