On Mon, Apr 19, 2021 at 8:32 AM Tzung-Bi Shih tzungbi@google.com wrote:
Commit 42a46434e9b1 ("pinctrl: add lock in mtk_rmw function.") uses mutex lock in mtk_rmw. However the function is possible called from atomic context.
For example call trace:
Please, shrink it to the necessary minimum.
mutex_lock+0x28/0x64 mtk_rmw+0x38/0x80 mtk_hw_set_value+0x100/0x138 mtk_gpio_set+0x48/0x58 gpiod_set_raw_value_commit+0xf4/0x110 gpiod_set_value_nocheck+0x4c/0x80 gpiod_set_value+0x4c/0x6c max98357a_daiops_trigger+0x8c/0x9c soc_pcm_trigger+0x5c/0x10c
The max98357a_daiops_trigger() could run in either atomic or non-atomic context. As a result, dmesg shows some similar messages: "BUG: sleeping function called from invalid context at kernel/locking/mutex.c:254".
Uses spin lock in mtk_rmw instead.
It's nice, but now the question is, can you have this function be called in a non-IRQ context concurrently with IRQ accessing registers?