spi: rspi: Fix register initialization while runtime-suspended
The Renesas RSPI/QSPI driver performs SPI controller register
initialization in its spi_operations.setup() callback, without calling
pm_runtime_get_sync() first, which may cause spurious failures.
So far this went unnoticed, as this SPI controller is typically used
with a single SPI NOR FLASH containing the boot loader:
1. If the device's module clock is still enabled (left enabled by the
bootloader, and not yet disabled by the clk_disable_unused() late
initcall), register initialization succeeds,
2. If the device's module clock is disabled, register writes don't
seem to cause lock-ups or crashes.
Data received in the first SPI message may be corrupted, though.
Subsequent SPI messages seem to be OK.
E.g. on r8a7791/koelsch, one bit is lost while receiving the 6th
byte of the JEDEC ID for the s25fl512s FLASH, corrupting that byte
and all later bytes. But until commit a2126b0a010905e5 ("mtd:
spi-nor: refine Spansion S25FL512S ID"), the 6th byte was not
considered for FLASH identification.
Fix this by moving all initialization from the .setup() to the
.prepare_message() callback. The latter is always called after the
device has been runtime-resumed by the SPI core.
This also makes the driver follow the rule that .setup() must not change
global driver state or register values, as that might break a transfer
in progress.
Fixes: 490c97747d5dc77d ("spi: rspi: Add runtime PM support, using spi core auto_runtime_pm")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed