linux.git/drivers/staging/fbtft, branch master

staging: fbtft: make dirty_lock IRQ-safe

2026-09-01T10:14:29+00:00

fbtft_mkdirty() can be reached from the fbcon rendering path while
processing printk() in hardirq context. Meanwhile, dirty_lock is also
taken by fbtft_deferred_io() in workqueue context with local interrupts
enabled.

Lockdep reports a possible IRQ lock inversion involving dirty_lock and
console_owner. A hardirq can interrupt a CPU holding dirty_lock and
enter the console rendering path, which can attempt to acquire
dirty_lock again.

The following lockdep report was observed on an RK3566 system with
CONFIG_PROVE_LOCKING enabled:

  WARNING: possible irq lock inversion dependency detected
  swapper/2/0 just changed the state of lock:
  (console_owner){-...}-{0:0}
  but this lock took another, HARDIRQ-unsafe lock in the past:
  (&par->dirty_lock){+.+.}-{2:2}

  CPU0                    CPU1
  ----                    ----
  lock(&par->dirty_lock);
                         local_irq_disable();
                         lock(console_owner);
                         lock(&par->dirty_lock);
  
    lock(console_owner);

  *** DEADLOCK ***

Use spin_lock_irqsave() for fbtft_mkdirty() and spin_lock_irq() for
fbtft_deferred_io(). They only access the dirty line range, so the
IRQ-off regions remain short.

Fixes: c296d5f9957c ("staging: fbtft: core support")
Signed-off-by: Hui Su 
Link: https://lore.kernel.org/lkml/20260804173712.176017-1-sh_def@163.com/
Reviewed-by: Nam Cao 
Link: https://patch.msgid.link/20260807150953.2811933-3-sh_def@163.com
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: fix typo in comment in fb_upd161704.c

2026-07-07T09:22:36+00:00

Fix spelling mistake found by codespell: "cencter" -> "center".

Signed-off-by: Tomasz Unger 
Reviewed-by: Andy Shevchenko 
Link: https://patch.msgid.link/20260611-upd161704-typo-v1-1-2e51387c3b28@yahoo.pl
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: Use sysfs_emit_at() to print to sysfs file

2026-07-07T09:22:31+00:00

This scnprintf() uses the wrong limit.  It should be "PAGE_SIZE - len"
instead of just PAGE_SIZE.  We're not going to hit the limit in real
life since we are printing at most FBTFT_GAMMA_MAX_VALUES_TOTAL (128)
u32 values, however, it's still worth fixing.

Use sysfs_emit_at() to fix this since this is a sysfs file.

Fixes: c296d5f9957c ("staging: fbtft: core support")
Signed-off-by: Dan Carpenter 
Reviewed-by: Andy Shevchenko 
Link: https://patch.msgid.link/ah_Y_Y2RtqeGxchF@stanley.mountain
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: remove unused function fbtft_write_gpio16_wr_latched

2026-05-04T14:49:10+00:00

The function fbtft_write_gpio16_wr_latched is not referenced anywhere
in the driver and only contains a stub implementation.

Remove it from the driver.

Signed-off-by: Hungyu Lin 
Reviewed-by: Andy Shevchenko 
Link: https://patch.msgid.link/20260430102529.25019-1-dennylin0707@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: Use %pe format specifier for error pointers

2026-04-27T11:01:56+00:00

The %pe format specifier resolves error pointers to their symbolic
representation. Previously %ld with PTR_ERR() was being used, %pe is a
better alternative.

Fixes the following coccinelle warnings reported by coccicheck:
WARNING: Consider using %pe to print PTR_ERR()

Testing: I do not own the hardware, therefore I could not perform
hardware testing. Compile tested only.

Signed-off-by: Mahad Ibrahim 
Link: https://patch.msgid.link/20260412144552.18493-1-mahad.ibrahim.dev@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: Update RA8875 Kconfig help description

2026-03-09T16:46:57+00:00

The current description is too brief. Update the description to
include the manufacturer (RAiO) and the supported resolution
(up to 800x480 pixels) to help users identify the correct driver.

Signed-off-by: Adam Azuddin 
Reviewed-by: Andy Shevchenko 
Link: https://patch.msgid.link/aaf9uQOBzCwQuff4@marchy
Signed-off-by: Greg Kroah-Hartman

fbtft: Update REAMDE to slow down the stream of undesired cleanups

2026-03-09T16:05:48+00:00

Lately the enormous amount of some untested cleanups started coming
to a mailing list. This adds an unneeded and undesired burden on
the reviewers and maintainers. Try to stop that by clearly state
what we accept and on what conditions in the README file.

Signed-off-by: Andy Shevchenko 
Link: https://patch.msgid.link/20260226080845.4081732-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: fb_tinylcd: replace udelay() with fsleep()

2026-02-23T14:43:56+00:00

fsleep() is the preferred modern API for flexible sleeping as it
automatically selects the best sleep mechanism based on the duration.
Replace udelay() with fsleep() to improve power efficiency.

init_display() is a driver initialization callback which runs in
sleeping context, so fsleep() is safe to use here.

Signed-off-by: Tomasz Unger 
Acked-by: Andy Shevchenko 
Link: https://patch.msgid.link/20260219142942.74087-1-tomasz.unger@yahoo.pl
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: Remove duplications of fbtft_set_addr_win()

2026-02-23T14:42:45+00:00

Lots of drivers duplicate the default fbtft_set_addr_win(). Just use the
default instead.

Signed-off-by: Nam Cao 
Reviewed-by: Andy Shevchenko 
Link: https://patch.msgid.link/20260213085927.3673653-1-namcao@linutronix.de
Signed-off-by: Greg Kroah-Hartman

staging: fbtft: fix unchecked write return value in fb_agm1264k-fl

2026-02-23T14:38:15+00:00

The second call to par->fbtftops.write() does not capture the return
value, so the subsequent error check tests a stale value from the
first write call. Add the missing assignment so the error check
applies to the correct write operation.

Signed-off-by: Artem Lytkin 
Acked-by: Andy Shevchenko 
Link: https://patch.msgid.link/20260207220523.3816-1-iprintercanon@gmail.com
Signed-off-by: Greg Kroah-Hartman