On Thu, Jun 20, 2024 at 05:26:57PM +0200, Dario Binacchi wrote: > From: Erwan Le Ray <erwan.leray@xxxxxxxxxxx> > > commit 33bb2f6ac3088936b7aad3cab6f439f91af0223c upstream. > > This patch reworks RX support over DMA to improve reliability: > - change dma buffer cyclic configuration by using 2 periods. DMA buffer > data are handled by a flip-flop between the 2 periods in order to avoid > risk of data loss/corruption > - change the size of dma buffer to 4096 to limit overruns > - add rx errors management (breaks, parity, framing and overrun). > When an error occurs on the uart line, the dma request line is masked at > HW level. The SW must 1st clear DMAR (dma request line enable), to > handle the error, then re-enable DMAR to recover. So, any correct data > is taken from the DMA buffer, before handling the error itself. Then > errors are handled from RDR/ISR/FIFO (e.g. in PIO mode). Last, DMA > reception is resumed. > - add a condition on DMA request line in DMA RX routines in order to > switch to PIO mode when no DMA request line is disabled, even if the DMA > channel is still enabled. > When the UART is wakeup source and is configured to use DMA for RX, any > incoming data that wakes up the system isn't correctly received. > At data reception, the irq_handler handles the WUF irq, and then the > data reception over DMA. > As the DMA transfer has been terminated at suspend, and will be restored > by resume callback (which has no yet been called by system), the data > can't be received. > The wake-up data has to be handled in PIO mode while suspend callback > has not been called. > > Signed-off-by: Valentin Caron <valentin.caron@xxxxxxxxxxx> > Signed-off-by: Erwan Le Ray <erwan.leray@xxxxxxxxxxx> > Link: https://lore.kernel.org/r/20211020150332.10214-3-erwan.leray@xxxxxxxxxxx > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > [ dario: fix conflicts for backport to v5.15. From the [1] series, only the > first patch was applied to the v5.15 branch. This caused a regression in > character reception, which can be fixed by applying the second patch. The > patch has been tested on the stm32f469-disco board. > [1] https://lore.kernel.org/all/20211020150332.10214-1-erwan.leray@xxxxxxxxxxx/. ] > Signed-off-by: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx> > > --- > > drivers/tty/serial/stm32-usart.c | 206 ++++++++++++++++++++++++------- > drivers/tty/serial/stm32-usart.h | 12 +- > 2 files changed, 165 insertions(+), 53 deletions(-) > Now queued up, thanks. greg k-h
