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drm/bridge: fix stack usage warning on old gcc

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Some older versions of gcc badly optimize code that passes
an inline function argument into another function by reference,
causing huge stack usage:

drivers/gpu/drm/bridge/tc358768.c: In function 'tc358768_bridge_pre_enable':
drivers/gpu/drm/bridge/tc358768.c:840:1: error: the frame size of 2256 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

Use a temporary variable as a workaround and add a comment pointing
to the gcc bug.

Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200428215408.4111675-1-arnd@arndb.de
This commit is contained in:
Arnd Bergmann 2020-04-28 23:53:54 +02:00 committed by Sam Ravnborg
parent 6d4f3e2bfc
commit 78b0d99a68
1 changed files with 3 additions and 1 deletions
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4
drivers/gpu/drm/bridge/tc358768.c
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@ -178,6 +178,8 @@ static int tc358768_clear_error(struct tc358768_priv *priv)
static void tc358768_write(struct tc358768_priv *priv, u32 reg, u32 val)
{
/* work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 */
int tmpval = val;
size_t count = 2;
if (priv->error)
@ -187,7 +189,7 @@ static void tc358768_write(struct tc358768_priv *priv, u32 reg, u32 val)
if (reg < 0x100 || reg >= 0x600)
count = 1;
priv->error = regmap_bulk_write(priv->regmap, reg, &val, count);
priv->error = regmap_bulk_write(priv->regmap, reg, &tmpval, count);
}
static void tc358768_read(struct tc358768_priv *priv, u32 reg, u32 *val)