Hi
Am 13.08.25 um 08:58 schrieb Thomas Zimmermann:
Hi
Am 13.08.25 um 03:38 schrieb Gary Chu(楚光庆):
Hi Thomas
This is what I've done in the yhgch_drm driver.
See the link below:
https://lore.kernel.org/all/20250808053508.52202-1-chuguangq...@inspur.com/T/#t
I see. I thought it was for an existing driver. In new drivers, please
don't use VRAM helpers any longer. VRAM helpers are based on TTM and
new drivers should use TTM directly. If you integrate the code from
VRAM helpers into your driver, you should be good.
Note that for reliably using TTM, your hardware requires at least 3
times the memory as the largest resolution+depth requires. The driver
says 1920*1200@32bpp, which amounts to ~9 MiB of VRAM. For TTM usage,
your device requires at least 32 MiB of VRAM available.
If your devices have smaller VRAM, rather use GEM SHMEM helpers instead.
And with TTM, buffer sharing is fairly hard to impossible. Shmem or DMA
helpers provide it out of the box.
Best regards
Thomas
Best regards
Thomas
In fact, through modifications in Patch v2, it allows only the
selection of
DRM_VRAM_HELPER in the driver.
See the link below:
https://lore.kernel.org/all/20250729060728.82402-1-chuguangq...@inspur.com/T/#m3e33f8e155275ea548223c21777c191ecd392159
Best regards
Chuguangqing
From: Thomas Zimmermann <tzimmerm...@suse.de>
To:chuguangqing <chuguangq...@inspur.com>; Maarten Lankhorst
<maarten.lankho...@linux.intel.com>; Maxime Ripard
<mrip...@kernel.org>;
David Airlie <airl...@gmail.com>; Simona Vetter <sim...@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org; linux-ker...@vger.kernel.org
Subject: Re: [PATCH 1/1] gpu: drm: fix compilation errors in
drm_vram_helper
Hi
Am 29.07.25 um 08:07 schrieb chuguangqing:
We encountered the following errors while compiling drm_vram_helper.ko
ERROR: modpost: "drm_gem_ttm_print_info"
[drivers/gpu/drm/drm_vram_helper.ko] undefined!
ERROR: modpost: "drm_gem_ttm_mmap"
[drivers/gpu/drm/drm_vram_helper.ko] undefined!
The functions drm_gem_ttm_mmap and drm_gem_ttm_print_info are
defined in drm_gem_ttm_helper.c. This patch adds
drm_gem_ttm_helper.o to
DRM_VRAM_HELPER to resolve the undefined symbol errors.
You need to select DRM_TTM_HELPER for your driver.
Best regards
Thomas
Signed-off-by: chuguangqing <chuguangq...@inspur.com>
---
drivers/gpu/drm/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index
4dafbdc8f86a..abbe32ddf6d0 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -125,7 +125,7 @@ drm_suballoc_helper-y := drm_suballoc.o
obj-$(CONFIG_DRM_SUBALLOC_HELPER) += drm_suballoc_helper.o
drm_vram_helper-y := drm_gem_vram_helper.o
-obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
+obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
+drm_gem_ttm_helper.o
drm_ttm_helper-y := drm_gem_ttm_helper.o
drm_ttm_helper-$(CONFIG_DRM_FBDEV_EMULATION) +=
drm_fbdev_ttm.o
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB
36809 (AG Nuernberg)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
