[PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Anand K Mistry]

If dma_map_sg() merges pages when creating the mapping, only the first
entries will have a valid sg_dma_address() and sg_dma_len(), followed by
entries with sg_dma_len() == 0.

Signed-off-by: Anand K Mistry <amistry@google.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index b04a3c2b111e09..f8fd8b98c30e3d 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
 
 	expected = sg_dma_address(sg->sgl);
 	for_each_sg(sg->sgl, s, sg->nents, i) {
+		if (!sg_dma_len(s))
+			break;
+
 		if (sg_dma_address(s) != expected) {
 			DRM_ERROR("sg_table is not contiguous");
 			ret = -EINVAL;
-- 
2.26.1.301.g55bc3eb7cb9-goog

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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Chun-Kuang Hu]

Hi, Anand:

Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
>
> If dma_map_sg() merges pages when creating the mapping, only the first
> entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> entries with sg_dma_len() == 0.
>
> Signed-off-by: Anand K Mistry <amistry@google.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> index b04a3c2b111e09..f8fd8b98c30e3d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
>
>         expected = sg_dma_address(sg->sgl);
>         for_each_sg(sg->sgl, s, sg->nents, i) {
> +               if (!sg_dma_len(s))
> +                       break;

I think this should be 'continue'

Regards,
Chun-Kuang.

> +
>                 if (sg_dma_address(s) != expected) {
>                         DRM_ERROR("sg_table is not contiguous");
>                         ret = -EINVAL;
> --
> 2.26.1.301.g55bc3eb7cb9-goog
>
>
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Anand K. Mistry]

[-- Attachment #1.1: Type: text/plain, Size: 2013 bytes --]

On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:

> Hi, Anand:
>
> Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> >
> > If dma_map_sg() merges pages when creating the mapping, only the first
> > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > entries with sg_dma_len() == 0.
> >
> > Signed-off-by: Anand K Mistry <amistry@google.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > @@ -224,6 +224,9 @@ struct drm_gem_object
> *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> >
> >         expected = sg_dma_address(sg->sgl);
> >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > +               if (!sg_dma_len(s))
> > +                       break;
>
> I think this should be 'continue'
>

scatterlist.h has the comment:
/*
 * These macros should be used after a dma_map_sg call has been done
 * to get bus addresses of each of the SG entries and their lengths.
 * You should only work with the number of sg entries dma_map_sg
 * returns, or alternatively stop on the first sg_dma_len(sg) which
 * is 0.
 */

So breaking on the first sg_dma_len(sg) == 0 appears to be (one of) the
documented approach.


> Regards,
> Chun-Kuang.
>
> > +
> >                 if (sg_dma_address(s) != expected) {
> >                         DRM_ERROR("sg_table is not contiguous");
> >                         ret = -EINVAL;
> > --
> > 2.26.1.301.g55bc3eb7cb9-goog
> >
> >
> > _______________________________________________
> > Linux-mediatek mailing list
> > Linux-mediatek@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-mediatek
>

[-- Attachment #1.2: Type: text/html, Size: 3040 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Anand K. Mistry]

On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
>
> Hi, Anand:
>
> Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> >
> > If dma_map_sg() merges pages when creating the mapping, only the first
> > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > entries with sg_dma_len() == 0.
> >
> > Signed-off-by: Anand K Mistry <amistry@google.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> >
> >         expected = sg_dma_address(sg->sgl);
> >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > +               if (!sg_dma_len(s))
> > +                       break;
>
> I think this should be 'continue'

scatterlist.h has the comment:
/*
 * These macros should be used after a dma_map_sg call has been done
 * to get bus addresses of each of the SG entries and their lengths.
 * You should only work with the number of sg entries dma_map_sg
 * returns, or alternatively stop on the first sg_dma_len(sg) which
 * is 0.
 */

So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
the documented approach.

>
> Regards,
> Chun-Kuang.
>
> > +
> >                 if (sg_dma_address(s) != expected) {
> >                         DRM_ERROR("sg_table is not contiguous");
> >                         ret = -EINVAL;
> > --
> > 2.26.1.301.g55bc3eb7cb9-goog
> >
> >
> > _______________________________________________
> > Linux-mediatek mailing list
> > Linux-mediatek@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Chun-Kuang Hu]

Hi, Anand,

Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
>
> On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> >
> > Hi, Anand:
> >
> > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > >
> > > If dma_map_sg() merges pages when creating the mapping, only the first
> > > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > > entries with sg_dma_len() == 0.
> > >
> > > Signed-off-by: Anand K Mistry <amistry@google.com>
> > > ---
> > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > >
> > >         expected = sg_dma_address(sg->sgl);
> > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > +               if (!sg_dma_len(s))
> > > +                       break;
> >
> > I think this should be 'continue'
>
> scatterlist.h has the comment:
> /*
>  * These macros should be used after a dma_map_sg call has been done
>  * to get bus addresses of each of the SG entries and their lengths.
>  * You should only work with the number of sg entries dma_map_sg
>  * returns, or alternatively stop on the first sg_dma_len(sg) which
>  * is 0.
>  */
>
> So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
> the documented approach.
>

Okay, you're right. So

Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

> >
> > Regards,
> > Chun-Kuang.
> >
> > > +
> > >                 if (sg_dma_address(s) != expected) {
> > >                         DRM_ERROR("sg_table is not contiguous");
> > >                         ret = -EINVAL;
> > > --
> > > 2.26.1.301.g55bc3eb7cb9-goog
> > >
> > >
> > > _______________________________________________
> > > Linux-mediatek mailing list
> > > Linux-mediatek@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Chun-Kuang Hu]

Hi, Anand,

Chun-Kuang Hu <chunkuang.hu@kernel.org> 於 2020年4月29日 週三 上午12:37寫道：
>
> Hi, Anand,
>
> Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
> >
> > On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > >
> > > Hi, Anand:
> > >
> > > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > > >
> > > > If dma_map_sg() merges pages when creating the mapping, only the first
> > > > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > > > entries with sg_dma_len() == 0.
> > > >
> > > > Signed-off-by: Anand K Mistry <amistry@google.com>

Author should sign off this patch, please give a sign off tag by author.

Regards,
Chun-Kuang.

> > > > ---
> > > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > > >  1 file changed, 3 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > > >
> > > >         expected = sg_dma_address(sg->sgl);
> > > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > > +               if (!sg_dma_len(s))
> > > > +                       break;
> > >
> > > I think this should be 'continue'
> >
> > scatterlist.h has the comment:
> > /*
> >  * These macros should be used after a dma_map_sg call has been done
> >  * to get bus addresses of each of the SG entries and their lengths.
> >  * You should only work with the number of sg entries dma_map_sg
> >  * returns, or alternatively stop on the first sg_dma_len(sg) which
> >  * is 0.
> >  */
> >
> > So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
> > the documented approach.
> >
>
> Okay, you're right. So
>
> Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
>
> > >
> > > Regards,
> > > Chun-Kuang.
> > >
> > > > +
> > > >                 if (sg_dma_address(s) != expected) {
> > > >                         DRM_ERROR("sg_table is not contiguous");
> > > >                         ret = -EINVAL;
> > > > --
> > > > 2.26.1.301.g55bc3eb7cb9-goog
> > > >
> > > >
> > > > _______________________________________________
> > > > Linux-mediatek mailing list
> > > > Linux-mediatek@lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Anand Mistry]

On Wed, May 6, 2020 at 10:25 AM Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
>
> Hi, Anand,
>
> Chun-Kuang Hu <chunkuang.hu@kernel.org> 於 2020年4月29日 週三 上午12:37寫道：
> >
> > Hi, Anand,
> >
> > Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
> > >
> > > On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > > >
> > > > Hi, Anand:
> > > >
> > > > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > > > >
> > > > > If dma_map_sg() merges pages when creating the mapping, only the first
> > > > > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > > > > entries with sg_dma_len() == 0.
> > > > >
> > > > > Signed-off-by: Anand K Mistry <amistry@google.com>
>
> Author should sign off this patch, please give a sign off tag by author.

Sorry, email issues meant i sent the patch from a different account.
Should I re-send the
patch from the same account as the sign-off line? I'm still working my
way through the kernel patch process.

>
> Regards,
> Chun-Kuang.
>
> > > > > ---
> > > > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > > > >  1 file changed, 3 insertions(+)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > > > >
> > > > >         expected = sg_dma_address(sg->sgl);
> > > > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > > > +               if (!sg_dma_len(s))
> > > > > +                       break;
> > > >
> > > > I think this should be 'continue'
> > >
> > > scatterlist.h has the comment:
> > > /*
> > >  * These macros should be used after a dma_map_sg call has been done
> > >  * to get bus addresses of each of the SG entries and their lengths.
> > >  * You should only work with the number of sg entries dma_map_sg
> > >  * returns, or alternatively stop on the first sg_dma_len(sg) which
> > >  * is 0.
> > >  */
> > >
> > > So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
> > > the documented approach.
> > >
> >
> > Okay, you're right. So
> >
> > Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> >
> > > >
> > > > Regards,
> > > > Chun-Kuang.
> > > >
> > > > > +
> > > > >                 if (sg_dma_address(s) != expected) {
> > > > >                         DRM_ERROR("sg_table is not contiguous");
> > > > >                         ret = -EINVAL;
> > > > > --
> > > > > 2.26.1.301.g55bc3eb7cb9-goog
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > Linux-mediatek mailing list
> > > > > Linux-mediatek@lists.infradead.org
> > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Chun-Kuang Hu]

Hi, Anand:

Anand Mistry <amistry@chromium.org> 於 2020年5月6日 週三 下午7:03寫道：
>
> On Wed, May 6, 2020 at 10:25 AM Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> >
> > Hi, Anand,
> >
> > Chun-Kuang Hu <chunkuang.hu@kernel.org> 於 2020年4月29日 週三 上午12:37寫道：
> > >
> > > Hi, Anand,
> > >
> > > Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
> > > >
> > > > On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > > > >
> > > > > Hi, Anand:
> > > > >
> > > > > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > > > > >
> > > > > > If dma_map_sg() merges pages when creating the mapping, only the first
> > > > > > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > > > > > entries with sg_dma_len() == 0.
> > > > > >
> > > > > > Signed-off-by: Anand K Mistry <amistry@google.com>
> >
> > Author should sign off this patch, please give a sign off tag by author.
>
> Sorry, email issues meant i sent the patch from a different account.
> Should I re-send the
> patch from the same account as the sign-off line? I'm still working my
> way through the kernel patch process.
>

If you want to use chromium account, you could simply reply this email
with a sign-off-by tag of chromium account.

Regards,
Chun-Kuang.

> >
> > Regards,
> > Chun-Kuang.
> >
> > > > > > ---
> > > > > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > > > > >  1 file changed, 3 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > > > > >
> > > > > >         expected = sg_dma_address(sg->sgl);
> > > > > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > > > > +               if (!sg_dma_len(s))
> > > > > > +                       break;
> > > > >
> > > > > I think this should be 'continue'
> > > >
> > > > scatterlist.h has the comment:
> > > > /*
> > > >  * These macros should be used after a dma_map_sg call has been done
> > > >  * to get bus addresses of each of the SG entries and their lengths.
> > > >  * You should only work with the number of sg entries dma_map_sg
> > > >  * returns, or alternatively stop on the first sg_dma_len(sg) which
> > > >  * is 0.
> > > >  */
> > > >
> > > > So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
> > > > the documented approach.
> > > >
> > >
> > > Okay, you're right. So
> > >
> > > Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> > >
> > > > >
> > > > > Regards,
> > > > > Chun-Kuang.
> > > > >
> > > > > > +
> > > > > >                 if (sg_dma_address(s) != expected) {
> > > > > >                         DRM_ERROR("sg_table is not contiguous");
> > > > > >                         ret = -EINVAL;
> > > > > > --
> > > > > > 2.26.1.301.g55bc3eb7cb9-goog
> > > > > >
> > > > > >
> > > > > > _______________________________________________
> > > > > > Linux-mediatek mailing list
> > > > > > Linux-mediatek@lists.infradead.org
> > > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Anand Mistry]

[-- Attachment #1.1: Type: text/plain, Size: 3868 bytes --]

On Wed, May 6, 2020 at 10:59 PM Chun-Kuang Hu <chunkuang.hu@kernel.org>
wrote:
>
> Hi, Anand:
>
> Anand Mistry <amistry@chromium.org> 於 2020年5月6日 週三 下午7:03寫道：
> >
> > On Wed, May 6, 2020 at 10:25 AM Chun-Kuang Hu <chunkuang.hu@kernel.org>
wrote:
> > >
> > > Hi, Anand,
> > >
> > > Chun-Kuang Hu <chunkuang.hu@kernel.org> 於 2020年4月29日 週三 上午12:37寫道：
> > > >
> > > > Hi, Anand,
> > > >
> > > > Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
> > > > >
> > > > > On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <
chunkuang.hu@kernel.org> wrote:
> > > > > >
> > > > > > Hi, Anand:
> > > > > >
> > > > > > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > > > > > >
> > > > > > > If dma_map_sg() merges pages when creating the mapping, only
the first
> > > > > > > entries will have a valid sg_dma_address() and sg_dma_len(),
followed by
> > > > > > > entries with sg_dma_len() == 0.
> > > > > > >
> > > > > > > Signed-off-by: Anand K Mistry <amistry@google.com>
> > >
> > > Author should sign off this patch, please give a sign off tag by
author.
> >
> > Sorry, email issues meant i sent the patch from a different account.
> > Should I re-send the
> > patch from the same account as the sign-off line? I'm still working my
> > way through the kernel patch process.
> >
>
> If you want to use chromium account, you could simply reply this email
> with a sign-off-by tag of chromium account.

Ack. As path of least resistance, here:

Signed-off-by: Anand K Mistry <amistry@chromium.org>


>
> Regards,
> Chun-Kuang.
>
> > >
> > > Regards,
> > > Chun-Kuang.
> > >
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > > > > > >  1 file changed, 3 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > @@ -224,6 +224,9 @@ struct drm_gem_object
*mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > > > > > >
> > > > > > >         expected = sg_dma_address(sg->sgl);
> > > > > > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > > > > > +               if (!sg_dma_len(s))
> > > > > > > +                       break;
> > > > > >
> > > > > > I think this should be 'continue'
> > > > >
> > > > > scatterlist.h has the comment:
> > > > > /*
> > > > >  * These macros should be used after a dma_map_sg call has been
done
> > > > >  * to get bus addresses of each of the SG entries and their
lengths.
> > > > >  * You should only work with the number of sg entries dma_map_sg
> > > > >  * returns, or alternatively stop on the first sg_dma_len(sg)
which
> > > > >  * is 0.
> > > > >  */
> > > > >
> > > > > So breaking on the first sg_dma_len(sg) == 0 appears to be (one
of)
> > > > > the documented approach.
> > > > >
> > > >
> > > > Okay, you're right. So
> > > >
> > > > Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> > > >
> > > > > >
> > > > > > Regards,
> > > > > > Chun-Kuang.
> > > > > >
> > > > > > > +
> > > > > > >                 if (sg_dma_address(s) != expected) {
> > > > > > >                         DRM_ERROR("sg_table is not
contiguous");
> > > > > > >                         ret = -EINVAL;
> > > > > > > --
> > > > > > > 2.26.1.301.g55bc3eb7cb9-goog
> > > > > > >
> > > > > > >
> > > > > > > _______________________________________________
> > > > > > > Linux-mediatek mailing list
> > > > > > > Linux-mediatek@lists.infradead.org
> > > > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek

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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Anand Mistry]

On Wed, May 6, 2020 at 10:59 PM Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
>
> Hi, Anand:
>
> Anand Mistry <amistry@chromium.org> 於 2020年5月6日 週三 下午7:03寫道：
> >
> > On Wed, May 6, 2020 at 10:25 AM Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > >
> > > Hi, Anand,
> > >
> > > Chun-Kuang Hu <chunkuang.hu@kernel.org> 於 2020年4月29日 週三 上午12:37寫道：
> > > >
> > > > Hi, Anand,
> > > >
> > > > Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
> > > > >
> > > > > On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > > > > >
> > > > > > Hi, Anand:
> > > > > >
> > > > > > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > > > > > >
> > > > > > > If dma_map_sg() merges pages when creating the mapping, only the first
> > > > > > > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > > > > > > entries with sg_dma_len() == 0.
> > > > > > >
> > > > > > > Signed-off-by: Anand K Mistry <amistry@google.com>
> > >
> > > Author should sign off this patch, please give a sign off tag by author.
> >
> > Sorry, email issues meant i sent the patch from a different account.
> > Should I re-send the
> > patch from the same account as the sign-off line? I'm still working my
> > way through the kernel patch process.
> >
>
> If you want to use chromium account, you could simply reply this email
> with a sign-off-by tag of chromium account.

Ack. This is fine for now. I'll try doing it better with the next patch.

Signed-off-by: Anand K Mistry <amistry@chromium.org>

>
> Regards,
> Chun-Kuang.
>
> > >
> > > Regards,
> > > Chun-Kuang.
> > >
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > > > > > >  1 file changed, 3 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > > > > > >
> > > > > > >         expected = sg_dma_address(sg->sgl);
> > > > > > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > > > > > +               if (!sg_dma_len(s))
> > > > > > > +                       break;
> > > > > >
> > > > > > I think this should be 'continue'
> > > > >
> > > > > scatterlist.h has the comment:
> > > > > /*
> > > > >  * These macros should be used after a dma_map_sg call has been done
> > > > >  * to get bus addresses of each of the SG entries and their lengths.
> > > > >  * You should only work with the number of sg entries dma_map_sg
> > > > >  * returns, or alternatively stop on the first sg_dma_len(sg) which
> > > > >  * is 0.
> > > > >  */
> > > > >
> > > > > So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
> > > > > the documented approach.
> > > > >
> > > >
> > > > Okay, you're right. So
> > > >
> > > > Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> > > >
> > > > > >
> > > > > > Regards,
> > > > > > Chun-Kuang.
> > > > > >
> > > > > > > +
> > > > > > >                 if (sg_dma_address(s) != expected) {
> > > > > > >                         DRM_ERROR("sg_table is not contiguous");
> > > > > > >                         ret = -EINVAL;
> > > > > > > --
> > > > > > > 2.26.1.301.g55bc3eb7cb9-goog
> > > > > > >
> > > > > > >
> > > > > > > _______________________________________________
> > > > > > > Linux-mediatek mailing list
> > > > > > > Linux-mediatek@lists.infradead.org
> > > > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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Re: [PATCH] drm/mediatek: stop iterating dma addresses when sg_dma_len() == 0

[Chun-Kuang Hu]

Hi, Anand:

Anand Mistry <amistry@chromium.org> 於 2020年5月7日 週四 下午7:56寫道：
>
> On Wed, May 6, 2020 at 10:59 PM Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> >
> > Hi, Anand:
> >
> > Anand Mistry <amistry@chromium.org> 於 2020年5月6日 週三 下午7:03寫道：
> > >
> > > On Wed, May 6, 2020 at 10:25 AM Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > > >
> > > > Hi, Anand,
> > > >
> > > > Chun-Kuang Hu <chunkuang.hu@kernel.org> 於 2020年4月29日 週三 上午12:37寫道：
> > > > >
> > > > > Hi, Anand,
> > > > >
> > > > > Anand K. Mistry <amistry@chromium.org> 於 2020年4月28日 週二 上午9:54寫道：
> > > > > >
> > > > > > On Sun, 26 Apr 2020 at 18:04, Chun-Kuang Hu <chunkuang.hu@kernel.org> wrote:
> > > > > > >
> > > > > > > Hi, Anand:
> > > > > > >
> > > > > > > Anand K Mistry <amistry@chromium.org> 於 2020年4月20日 週一 下午2:09寫道：
> > > > > > > >
> > > > > > > > If dma_map_sg() merges pages when creating the mapping, only the first
> > > > > > > > entries will have a valid sg_dma_address() and sg_dma_len(), followed by
> > > > > > > > entries with sg_dma_len() == 0.
> > > > > > > >
> > > > > > > > Signed-off-by: Anand K Mistry <amistry@google.com>
> > > >
> > > > Author should sign off this patch, please give a sign off tag by author.
> > >
> > > Sorry, email issues meant i sent the patch from a different account.
> > > Should I re-send the
> > > patch from the same account as the sign-off line? I'm still working my
> > > way through the kernel patch process.
> > >
> >
> > If you want to use chromium account, you could simply reply this email
> > with a sign-off-by tag of chromium account.
>
> Ack. As path of least resistance, here:
>
> Signed-off-by: Anand K Mistry <amistry@chromium.org>
>

Applied to mediatek-drm-next [1], thanks.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next

Regards,
Chun-Kuang.

>
> >
> > Regards,
> > Chun-Kuang.
> >
> > > >
> > > > Regards,
> > > > Chun-Kuang.
> > > >
> > > > > > > > ---
> > > > > > > >  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
> > > > > > > >  1 file changed, 3 insertions(+)
> > > > > > > >
> > > > > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > > index b04a3c2b111e09..f8fd8b98c30e3d 100644
> > > > > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> > > > > > > > @@ -224,6 +224,9 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
> > > > > > > >
> > > > > > > >         expected = sg_dma_address(sg->sgl);
> > > > > > > >         for_each_sg(sg->sgl, s, sg->nents, i) {
> > > > > > > > +               if (!sg_dma_len(s))
> > > > > > > > +                       break;
> > > > > > >
> > > > > > > I think this should be 'continue'
> > > > > >
> > > > > > scatterlist.h has the comment:
> > > > > > /*
> > > > > >  * These macros should be used after a dma_map_sg call has been done
> > > > > >  * to get bus addresses of each of the SG entries and their lengths.
> > > > > >  * You should only work with the number of sg entries dma_map_sg
> > > > > >  * returns, or alternatively stop on the first sg_dma_len(sg) which
> > > > > >  * is 0.
> > > > > >  */
> > > > > >
> > > > > > So breaking on the first sg_dma_len(sg) == 0 appears to be (one of)
> > > > > > the documented approach.
> > > > > >
> > > > >
> > > > > Okay, you're right. So
> > > > >
> > > > > Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> > > > >
> > > > > > >
> > > > > > > Regards,
> > > > > > > Chun-Kuang.
> > > > > > >
> > > > > > > > +
> > > > > > > >                 if (sg_dma_address(s) != expected) {
> > > > > > > >                         DRM_ERROR("sg_table is not contiguous");
> > > > > > > >                         ret = -EINVAL;
> > > > > > > > --
> > > > > > > > 2.26.1.301.g55bc3eb7cb9-goog
> > > > > > > >
> > > > > > > >
> > > > > > > > _______________________________________________
> > > > > > > > Linux-mediatek mailing list
> > > > > > > > Linux-mediatek@lists.infradead.org
> > > > > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
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