Thomas Zimmermann
2025-Aug-21 08:17 UTC
[PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()
Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 8.
Push the current calculation into the only direct caller imx. Imx's
hardware requires the framebuffer width to be aligned to 8. The
driver's current approach is actually incorrect, as it only guarantees
this implicitly and requires bpp to be a multiple of 8 already. A
later commit will fix this problem by aligning the scanline pitch
such that an aligned width still fits into each scanline's memory.
A number of other drivers are build on top of gem-dma helpers and
implement their own dumb-buffer allocation. These drivers invoke
drm_gem_dma_dumb_create_internal(), which is not affected by this
commit.
v5:
- avoid reset of arguments (Tomi)
Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
---
drivers/gpu/drm/drm_gem_dma_helper.c | 7 +++++--
drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c
b/drivers/gpu/drm/drm_gem_dma_helper.c
index 4f0320df858f..ab1a70b1d6f1 100644
--- a/drivers/gpu/drm/drm_gem_dma_helper.c
+++ b/drivers/gpu/drm/drm_gem_dma_helper.c
@@ -20,6 +20,7 @@
#include <drm/drm.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_vma_manager.h>
@@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv,
struct drm_mode_create_dumb *args)
{
struct drm_gem_dma_object *dma_obj;
+ int ret;
- args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
- args->size = args->pitch * args->height;
+ ret = drm_mode_size_dumb(drm, args, SZ_8, 0);
+ if (ret)
+ return ret;
dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
&args->handle);
diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
index ec5fd9a01f1e..af4a30311e18 100644
--- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
@@ -145,8 +145,10 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
int ret;
args->width = ALIGN(width, 8);
+ args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+ args->size = args->pitch * args->height;
- ret = drm_gem_dma_dumb_create(file_priv, drm, args);
+ ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
if (ret)
return ret;
--
2.50.1
Ludovic.Desroches at microchip.com
2025-Nov-25 14:40 UTC
[PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()
On 8/21/25 10:17, Thomas Zimmermann wrote:> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and > buffer size. Align the pitch to a multiple of 8. > > Push the current calculation into the only direct caller imx. Imx's > hardware requires the framebuffer width to be aligned to 8. The > driver's current approach is actually incorrect, as it only guarantees > this implicitly and requires bpp to be a multiple of 8 already. A > later commit will fix this problem by aligning the scanline pitch > such that an aligned width still fits into each scanline's memory. > > A number of other drivers are build on top of gem-dma helpers and > implement their own dumb-buffer allocation. These drivers invoke > drm_gem_dma_dumb_create_internal(), which is not affected by this > commit. > > v5: > - avoid reset of arguments (Tomi) > > Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de> > Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com> > --- > drivers/gpu/drm/drm_gem_dma_helper.c | 7 +++++-- > drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++- > 2 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c > index 4f0320df858f..ab1a70b1d6f1 100644 > --- a/drivers/gpu/drm/drm_gem_dma_helper.c > +++ b/drivers/gpu/drm/drm_gem_dma_helper.c > @@ -20,6 +20,7 @@ > #include <drm/drm.h> > #include <drm/drm_device.h> > #include <drm/drm_drv.h> > +#include <drm/drm_dumb_buffers.h> > #include <drm/drm_gem_dma_helper.h> > #include <drm/drm_vma_manager.h> > > @@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv, > struct drm_mode_create_dumb *args) > { > struct drm_gem_dma_object *dma_obj; > + int ret; > > - args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8); > - args->size = args->pitch * args->height; > + ret = drm_mode_size_dumb(drm, args, SZ_8, 0); > + if (ret) > + return ret;Hi, Was it intentional for this change to alter the pitch? The alignment requirement has been updated?from 8-bit alignment to 64-bit alignment. Since the pitch is expressed in bytes, we should pass SZ_1 instead of SZ_8 for hw_patch_align. For example, for an 850?480 framebuffer at 16 bpp, the pitch should be 1700 bytes. With the new alignment, the pitch becomes 1704 bytes. Please let me know if you?d like me to submit a fix. Regards, Ludovic> > dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size, > &args->handle); > diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c > index ec5fd9a01f1e..af4a30311e18 100644 > --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c > +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c > @@ -145,8 +145,10 @@ static int imx_drm_dumb_create(struct drm_file *file_priv, > int ret; > > args->width = ALIGN(width, 8); > + args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8); > + args->size = args->pitch * args->height; > > - ret = drm_gem_dma_dumb_create(file_priv, drm, args); > + ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args); > if (ret) > return ret; >
Thomas Zimmermann
2025-Nov-25 15:03 UTC
[PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()
Hi Am 25.11.25 um 15:39 schrieb Ludovic.Desroches at microchip.com:> On 8/21/25 10:17, Thomas Zimmermann wrote: >> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and >> buffer size. Align the pitch to a multiple of 8.I missed a chance to explain it here. :/>> >> Push the current calculation into the only direct caller imx. Imx's >> hardware requires the framebuffer width to be aligned to 8. The >> driver's current approach is actually incorrect, as it only guarantees >> this implicitly and requires bpp to be a multiple of 8 already. A >> later commit will fix this problem by aligning the scanline pitch >> such that an aligned width still fits into each scanline's memory. >> >> A number of other drivers are build on top of gem-dma helpers and >> implement their own dumb-buffer allocation. These drivers invoke >> drm_gem_dma_dumb_create_internal(), which is not affected by this >> commit. >> >> v5: >> - avoid reset of arguments (Tomi) >> >> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de> >> Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com> >> --- >> drivers/gpu/drm/drm_gem_dma_helper.c | 7 +++++-- >> drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++- >> 2 files changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c >> index 4f0320df858f..ab1a70b1d6f1 100644 >> --- a/drivers/gpu/drm/drm_gem_dma_helper.c >> +++ b/drivers/gpu/drm/drm_gem_dma_helper.c >> @@ -20,6 +20,7 @@ >> #include <drm/drm.h> >> #include <drm/drm_device.h> >> #include <drm/drm_drv.h> >> +#include <drm/drm_dumb_buffers.h> >> #include <drm/drm_gem_dma_helper.h> >> #include <drm/drm_vma_manager.h> >> >> @@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv, >> struct drm_mode_create_dumb *args) >> { >> struct drm_gem_dma_object *dma_obj; >> + int ret; >> >> - args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8); >> - args->size = args->pitch * args->height; >> + ret = drm_mode_size_dumb(drm, args, SZ_8, 0); >> + if (ret) >> + return ret; > Hi, > > Was it intentional for this change to alter the pitch?Most hardware does not need the pitch to be of a certain alignment. But these buffers are possibly shared with other hardware, which sometimes needs alignment to certain values. Using SZ_8 improves compatible with that hardware.> > The alignment requirement has been updated?from 8-bit alignment to > 64-bit alignment. Since the pitch is expressed in bytes, we should pass > SZ_1 instead of SZ_8 for hw_patch_align. > > For example, for an 850?480 framebuffer at 16 bpp, the pitch should be > 1700 bytes. With the new alignment, the pitch becomes 1704 bytes.Many display modes have an 8-byte alignment in their width. 850 pixels is somewhat of an exception.> > Please let me know if you?d like me to submit a fix.Do you see a bug with your hardware? Unless this creates a real problem, I'd like to keep it as it is now. Best regards Thomas> > Regards, > Ludovic > > >> >> dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size, >> &args->handle); >> diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c >> index ec5fd9a01f1e..af4a30311e18 100644 >> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c >> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c >> @@ -145,8 +145,10 @@ static int imx_drm_dumb_create(struct drm_file *file_priv, >> int ret; >> >> args->width = ALIGN(width, 8); >> + args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8); >> + args->size = args->pitch * args->height; >> >> - ret = drm_gem_dma_dumb_create(file_priv, drm, args); >> + ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args); >> if (ret) >> return ret; >>-- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 N?rnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG N?rnberg)