On 1/12/26 22:16, Greg KH wrote:
On Mon, Jan 12, 2026 at 08:59:09PM -0800, Chintan Patel wrote:
Replace direct accesses to info->dev with fb_dbg() and fb_info()
helpers to avoid build failures when CONFIG_FB_DEVICE=n.
Why is there a fb_* specific logging helper? dev_info() and dev_dbg()
should be used instead.
You’re correct that dev_dbg()/dev_info() are the standard logging APIs.
The reason I switched to fb_dbg()/fb_info() is not stylistic: direct
dereferences of info->dev / fb_info->dev are invalid when
CONFIG_FB_DEVICE=n, which causes compile-time errors.
fb_dbg() and fb_info() are framebuffer-specific helpers that handle
this case correctly, allowing logging without touching info->dev.
Fixes: a06d03f9f238 ("staging: fbtft: Make FB_DEVICE dependency optional")
Is this really a bug?
The build failure occurs when CONFIG_FB_DEVICE=n, where direct
dereferences of info->dev / fb_info->dev are not valid. This was
reported by the kernel test robot.
That said, I’m fine dropping the Fixes tag if you don’t consider this a
regression.
Reported-by: kernel test robot <[email protected]>
Closes:
https://lore.kernel.org/oe-kbuild-all/[email protected]
Signed-off-by: Chintan Patel <[email protected]>
Changes in v6:
- Switch debug/info logging to fb_dbg() and fb_info()(suggested by Thomas
Zimmermann)
- Drop dev_of_fbinfo() usage in favor of framebuffer helpers that implicitly
handle the debug/info context.
- Drop __func__ usage per review feedback(suggested by greg k-h)
- Add Fixes tag for a06d03f9f238 ("staging: fbtft: Make FB_DEVICE dependency
optional")
(suggested by Andy Shevchenko)
Changes in v5:
- Initial attempt to replace info->dev accesses using
dev_of_fbinfo() helper
---
The changelog stuff goes below the --- line.
Ack.
drivers/staging/fbtft/fbtft-core.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/drivers/staging/fbtft/fbtft-core.c
b/drivers/staging/fbtft/fbtft-core.c
index 8a5ccc8ae0a1..1b3b62950205 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -365,9 +365,9 @@ static int fbtft_fb_setcolreg(unsigned int regno, unsigned
int red,
unsigned int val;
int ret = 1;
- dev_dbg(info->dev,
- "%s(regno=%u, red=0x%X, green=0x%X, blue=0x%X, trans=0x%X)\n",
- __func__, regno, red, green, blue, transp);
+ fb_dbg(info,
+ "regno=%u, red=0x%X, green=0x%X, blue=0x%X, trans=0x%X\n",
+ regno, red, green, blue, transp);
I dont understand what is wrong with the existing dev_dbg() line (with
the exception that __func__ should not be in it.
switch (info->fix.visual) {
case FB_VISUAL_TRUECOLOR:
@@ -391,8 +391,7 @@ static int fbtft_fb_blank(int blank, struct fb_info *info)
struct fbtft_par *par = info->par;
int ret = -EINVAL;
- dev_dbg(info->dev, "%s(blank=%d)\n",
- __func__, blank);
+ fb_dbg(info, "blank=%d\n", blank);
Same here, what's wrong with dev_dbg()?
Same reason: dereferencing info->dev is invalid when CONFIG_FB_DEVICE=n.
fb_dbg() handles this correctly without needing info->dev.
if (!par->fbtftops.blank)
return ret;
@@ -793,11 +792,11 @@ int fbtft_register_framebuffer(struct fb_info *fb_info)
if (spi)
sprintf(text2, ", spi%d.%d at %d MHz", spi->controller->bus_num,
spi_get_chipselect(spi, 0), spi->max_speed_hz /
1000000);
- dev_info(fb_info->dev,
- "%s frame buffer, %dx%d, %d KiB video memory%s, fps=%lu%s\n",
- fb_info->fix.id, fb_info->var.xres, fb_info->var.yres,
- fb_info->fix.smem_len >> 10, text1,
- HZ / fb_info->fbdefio->delay, text2);
+ fb_info(fb_info,
+ "%s frame buffer, %dx%d, %d KiB video memory%s, fps=%lu%s\n",
+ fb_info->fix.id, fb_info->var.xres, fb_info->var.yres,
+ fb_info->fix.smem_len >> 10, text1,
+ HZ / fb_info->fbdefio->delay, text2);
When drivers work properly, they are quiet. Why is this needed at all
except as a debug message?
Agreed. The informational message during framebuffer registration is not
necessary. I will either remove it entirely or convert it to a
debug-only message.
I’ll rework the patch accordingly and resend.
Thanks again for the guidance.
