linux-kernel - [PATCH v1 1/2] drivers/video/fbdev: don't select DMA

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Message-Id: <20210408092011.52763-2-david@redhat.com>
Date:   Thu,  8 Apr 2021 11:20:10 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Joel Stanley <joel@....id.au>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Andrew Jeffery <andrew@...id.au>,
        Lucas Stach <l.stach@...gutronix.de>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        Mike Rapoport <rppt@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Michal Simek <michal.simek@...inx.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Peter Collingbourne <pcc@...gle.com>,
        linux-aspeed@...ts.ozlabs.org, dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        etnaviv@...ts.freedesktop.org, linux-fbdev@...r.kernel.org
Subject: [PATCH v1 1/2] drivers/video/fbdev: don't select DMA_CMA

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 DRM_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 <david@...hat.com>
---
 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