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drm: panel: fix excessive stack usage in td028ttec1_prepare

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With gcc -O3 in combination with the structleak plug, the compiler can
inline very aggressively, leading to rather large stack usage:

drivers/gpu/drm/panel/panel-tpo-td028ttec1.c: In function 'td028ttec1_prepare':
drivers/gpu/drm/panel/panel-tpo-td028ttec1.c:233:1: error: the frame size of 2768 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
 }

Marking jbt_reg_write_*() as noinline avoids the case where
multiple instances of this function get inlined into the same
stack frame and each one adds a copy of 'tx_buf'.

The compiler is clearly making some bad decisions here, but I
did not open a new bug report as this only happens in combination
with the structleak plugin.

This fixes mmtom ("init/Kconfig: enable -O3 for all arches")

Link: https://lore.kernel.org/lkml/CAK8P3a3jAnFZA3GFRtdYdg1-i-oih3pOQzkkrK-X3BGsFrMiZQ@mail.gmail.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org> [fix indent]
Link: https://patchwork.freedesktop.org/patch/msgid/20200108135116.3687988-1-arnd@arndb.de
This commit is contained in:
Arnd Bergmann 2020-01-08 14:51:05 +01:00 committed by Sam Ravnborg
parent 0980939d2a
commit dba9bf0a98
1 changed files with 12 additions and 5 deletions
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17
drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
View file

@ -86,7 +86,12 @@ struct td028ttec1_panel {
#define to_td028ttec1_device(p) container_of(p, struct td028ttec1_panel, panel)
static int jbt_ret_write_0(struct td028ttec1_panel *lcd, u8 reg, int *err)
/*
* noinline_for_stack so we don't get multiple copies of tx_buf
* on the stack in case of gcc-plugin-structleak
*/
static int noinline_for_stack
jbt_ret_write_0(struct td028ttec1_panel *lcd, u8 reg, int *err)
{
struct spi_device *spi = lcd->spi;
u16 tx_buf = JBT_COMMAND | reg;
@ -105,8 +110,9 @@ static int jbt_ret_write_0(struct td028ttec1_panel *lcd, u8 reg, int *err)
return ret;
}
static int jbt_reg_write_1(struct td028ttec1_panel *lcd,
u8 reg, u8 data, int *err)
static int noinline_for_stack
jbt_reg_write_1(struct td028ttec1_panel *lcd,
u8 reg, u8 data, int *err)
{
struct spi_device *spi = lcd->spi;
u16 tx_buf[2];
@ -128,8 +134,9 @@ static int jbt_reg_write_1(struct td028ttec1_panel *lcd,
return ret;
}
static int jbt_reg_write_2(struct td028ttec1_panel *lcd,
u8 reg, u16 data, int *err)
static int noinline_for_stack
jbt_reg_write_2(struct td028ttec1_panel *lcd,
u8 reg, u16 data, int *err)
{
struct spi_device *spi = lcd->spi;
u16 tx_buf[3];