spi: rspi: Fix register initialization while runtime-suspended

Browse source

commit 42bdaaece1 upstream.

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 a2126b0a01 ("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: 490c97747d ("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>
[bwh: Backported to 3.16: s/(controller|ctlr)/master/g]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

This commit is contained in:

Geert Uytterhoeven 2019-03-12 19:43:31 +01:00 • committed by Ben Hutchings

parent a3d313e330

commit 2987155e8f

1 changed files with 16 additions and 23 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

39

drivers/spi/spi-rspi.c

View file