[PATCH v2 0/2] drivers: don't select DMA_CMA or CMA

Trying to set CONFIG_CMA=y with CONFIG_DMA_CMA=n revealed that we have
three drivers that select these options. Random drivers should not
override user settings of such core knobs. Let's use "imply DMA_CMA"
instead, such that user configuration and dependencies are respected.

v1 -> v2:
- Fix DRM_CMA -> DMA_CMA

Cc: Joel Stanley <joel@jms.id.au>
Cc: David Airlie <redacted>
Cc: Daniel Vetter <redacted>
Cc: Andrew Jeffery <redacted>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bartlomiej Zolnierkiewicz <redacted>
Cc: Linus Walleij <redacted>
Cc: Michal Simek <redacted>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Randy Dunlap <redacted>
Cc: Peter Collingbourne <redacted>
Cc: linux-aspeed@lists.ozlabs.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: etnaviv@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org

David Hildenbrand (2):
  drivers/video/fbdev: don't select DMA_CMA
  drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv

 drivers/gpu/drm/aspeed/Kconfig  | 3 +--
 drivers/gpu/drm/etnaviv/Kconfig | 3 +--
 drivers/video/fbdev/Kconfig     | 2 +-
 3 files changed, 3 insertions(+), 5 deletions(-)

-- 
2.30.2

Random drivers should not override a user configuration of core knobs
(e.g., CONFIG_DMA_CMA=n). Use "imply" instead, to still respect
dependencies and manual overrides.

"This is similar to "select" as it enforces a lower limit on another
 symbol except that the "implied" symbol's value may still be set to n
 from a direct dependency or with a visible prompt."

Implying DMA_CMA should be sufficient, as that depends on CMA.

Note: If this is a real dependency, we should use "depends on DMA_CMA"
instead -  but I assume the driver can work without CMA just fine --
esp. when we wouldn't have HAVE_DMA_CONTIGUOUS or CMA right now.

Signed-off-by: David Hildenbrand <redacted>
---
 drivers/video/fbdev/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index 4f02db65dede..d37cd5341e1b 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig

@@ -2186,7 +2186,7 @@ config FB_HYPERV
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
 	select FB_DEFERRED_IO
-	select DMA_CMA if HAVE_DMA_CONTIGUOUS && CMA
+	imply DMA_CMA
 	help
 	  This framebuffer driver supports Microsoft Hyper-V Synthetic Video.
 

-- 
2.30.2

Random drivers should not override a user configuration of core knobs
(e.g., CONFIG_DMA_CMA=n). Use "imply" instead, to still respect
dependencies and manual overrides.

"This is similar to "select" as it enforces a lower limit on another
 symbol except that the "implied" symbol's value may still be set to n
 from a direct dependency or with a visible prompt."

Implying DMA_CMA should be sufficient, as that depends on CMA.

Note: If this is a real dependency, we should use "depends on DMA_CMA"
instead -  but I assume the driver can work without CMA just fine --
esp. when we wouldn't have HAVE_DMA_CONTIGUOUS right now.

Signed-off-by: David Hildenbrand <redacted>
---
 drivers/gpu/drm/aspeed/Kconfig  | 3 +--
 drivers/gpu/drm/etnaviv/Kconfig | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/aspeed/Kconfig b/drivers/gpu/drm/aspeed/Kconfig
index 5e95bcea43e9..b35bb1aa9b91 100644
--- a/drivers/gpu/drm/aspeed/Kconfig
+++ b/drivers/gpu/drm/aspeed/Kconfig

@@ -6,9 +6,8 @@ config DRM_ASPEED_GFX
 	depends on MMU
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
-	select DMA_CMA if HAVE_DMA_CONTIGUOUS
-	select CMA if HAVE_DMA_CONTIGUOUS
 	select MFD_SYSCON
+	imply DMA_CMA
 	help
 	  Chose this option if you have an ASPEED AST2500 SOC Display
 	  Controller (aka GFX).

diff --git a/drivers/gpu/drm/etnaviv/Kconfig b/drivers/gpu/drm/etnaviv/Kconfig
index faa7fc68b009..5f5576b7221a 100644
--- a/drivers/gpu/drm/etnaviv/Kconfig
+++ b/drivers/gpu/drm/etnaviv/Kconfig

@@ -9,9 +9,8 @@ config DRM_ETNAVIV
 	select THERMAL if DRM_ETNAVIV_THERMAL
 	select TMPFS
 	select WANT_DEV_COREDUMP
-	select CMA if HAVE_DMA_CONTIGUOUS
-	select DMA_CMA if HAVE_DMA_CONTIGUOUS
 	select DRM_SCHED
+	imply DMA_CMA
 	help
 	  DRM driver for Vivante GPUs.
 

-- 
2.30.2

On Thu, Apr 08, 2021 at 12:05:21PM +0200, David Hildenbrand wrote:

Trying to set CONFIG_CMA=y with CONFIG_DMA_CMA=n revealed that we have
three drivers that select these options. Random drivers should not
override user settings of such core knobs. Let's use "imply DMA_CMA"
instead, such that user configuration and dependencies are respected.

v1 -> v2:
- Fix DRM_CMA -> DMA_CMA

Cc: Joel Stanley <joel@jms.id.au>
Cc: David Airlie <redacted>
Cc: Daniel Vetter <redacted>
Cc: Andrew Jeffery <redacted>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bartlomiej Zolnierkiewicz <redacted>
Cc: Linus Walleij <redacted>
Cc: Michal Simek <redacted>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Randy Dunlap <redacted>
Cc: Peter Collingbourne <redacted>
Cc: linux-aspeed@lists.ozlabs.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: etnaviv@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org

David Hildenbrand (2):
  drivers/video/fbdev: don't select DMA_CMA
  drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv

 drivers/gpu/drm/aspeed/Kconfig  | 3 +--
 drivers/gpu/drm/etnaviv/Kconfig | 3 +--
 drivers/video/fbdev/Kconfig     | 2 +-
 3 files changed, 3 insertions(+), 5 deletions(-)

Acked-by: Mike Rapoport <redacted>

-- 
2.30.2

-- 
Sincerely yours,
Mike.