target/linux/ath79/patches-5.10/0054-spi-always-write-cs.patch

   1 Upstream commit d40f0b6f2e21 ("spi: Avoid settingthe chip select if
   2 we don't need to") causes the SPI CS only to be asserted once and not
   3 if it's state stays the same.
   4
   5 This seems to cause problems with the SPI on the AR724x and the AR913x
   6 (but not the AR71xx). AR934x and subsequent chips do not look affected.
   7
   8 ToDo:
   9  - Analyze if this is a hardware bug or a bug in the software.
  10  - Send a cleaned up patch upstream.
  11
  12 Signed-off-by: David Bauer <mail@david-bauer.net>
  13
  14 --- a/drivers/spi/spi.c
  15 +++ b/drivers/spi/spi.c
  16 @@ -791,6 +791,7 @@ static void spi_set_cs(struct spi_device
  17  {
  18         bool enable1 = enable;
  19
  20 +#if 0
  21         /*
  22          * Avoid calling into the driver (or doing delays) if the chip select
  23          * isn't actually changing from the last time this was called.
  24 @@ -801,6 +802,7 @@ static void spi_set_cs(struct spi_device
  25
  26         spi->controller->last_cs_enable = enable;
  27         spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH;
  28 +#endif
  29
  30         if (!spi->controller->set_cs_timing) {
  31                 if (enable1)