Clang reports that pixpaper_panel_hw_init() exceeds the 8 KB stack
frame limit:
drivers/gpu/drm/tiny/pixpaper.c:579:12: warning:
stack frame size (20024) exceeds limit (8192)
in 'pixpaper_panel_hw_init'
This warning occurs because the compiler aggressively inlines
pixpaper_send_cmd() and pixpaper_send_data() into
pixpaper_panel_hw_init(), which inflates the estimated stack usage.
Mark these two helper functions as 'noinline' to prevent inlining.
This significantly reduces the reported stack usage without changing
runtime behavior.
Reported-by: kernel test robot <[email protected]>
Closes:
https://lore.kernel.org/oe-kbuild-all/[email protected]/
Fixes: c9e70639f591 ("drm: tiny: Add support for Mayqueen Pixpaper e-ink panel")
Signed-off-by: LiangCheng Wang <[email protected]>
---
When building with Clang and frame size warnings enabled
(-Wframe-larger-than=8192), the compiler reports that
pixpaper_panel_hw_init() consumes over 20 KB of stack space:
drivers/gpu/drm/tiny/pixpaper.c:579:12: warning:
stack frame size (20024) exceeds limit (8192)
in 'pixpaper_panel_hw_init'
This happens because Clang aggressively inlines
pixpaper_send_cmd() and pixpaper_send_data() into
pixpaper_panel_hw_init(), causing the calculated stack usage
to balloon far beyond the warning threshold.
The fix is straightforward: mark these two helper functions as
'noinline' to prevent inlining. This reduces the reported stack
usage to within normal limits without changing runtime behavior.
---
drivers/gpu/drm/tiny/pixpaper.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/tiny/pixpaper.c b/drivers/gpu/drm/tiny/pixpaper.c
index
32598fb2fee7fcdea3ea0696c2bf54404fcffa2e..70e3239adfd0f86f92551991872486380489fb9b
100644
--- a/drivers/gpu/drm/tiny/pixpaper.c
+++ b/drivers/gpu/drm/tiny/pixpaper.c
@@ -536,7 +536,7 @@ static void pixpaper_spi_sync(struct spi_device *spi,
struct spi_message *msg,
err->errno_code = ret;
}
-static void pixpaper_send_cmd(struct pixpaper_panel *panel, u8 cmd,
+static noinline void pixpaper_send_cmd(struct pixpaper_panel *panel, u8 cmd,
struct pixpaper_error_ctx *err)
{
if (err->errno_code)
@@ -556,7 +556,7 @@ static void pixpaper_send_cmd(struct pixpaper_panel *panel,
u8 cmd,
pixpaper_spi_sync(panel->spi, &msg, err);
}
-static void pixpaper_send_data(struct pixpaper_panel *panel, u8 data,
+static noinline void pixpaper_send_data(struct pixpaper_panel *panel, u8 data,
struct pixpaper_error_ctx *err)
{
if (err->errno_code)
---
base-commit: d127176862a93c4b3216bda533d2bee170af5e71
change-id: 20251031-fix_202510270858-2e4643b00545
Best regards,
--
LiangCheng Wang <[email protected]>
