spi: fsi: Fix clock running too fast

Use a clock divider tuned to a 200MHz FSI bus frequency (the maximum). Use
of the previous divider at 200MHz results in corrupt data from endpoint
devices. Ideally the clock divider would be calculated from the FSI clock,
but that would require some significant work on the FSI driver. With FSI
frequencies slower than 200MHz, the SPI clock will simply run slower, but
safely.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20200909222857.28653-3-eajames@linux.ibm.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Brad Bishop 2020-09-09 17:28:53 -05:00 committed by Mark Brown
parent 2b3cef0fc7
commit 0b546bbe94
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GPG key ID: 24D68B725D5487D0

View file

@ -350,7 +350,7 @@ static int fsi_spi_transfer_init(struct fsi_spi *ctx)
u64 status = 0ULL;
u64 wanted_clock_cfg = SPI_FSI_CLOCK_CFG_ECC_DISABLE |
SPI_FSI_CLOCK_CFG_SCK_NO_DEL |
FIELD_PREP(SPI_FSI_CLOCK_CFG_SCK_DIV, 4);
FIELD_PREP(SPI_FSI_CLOCK_CFG_SCK_DIV, 19);
end = jiffies + msecs_to_jiffies(SPI_FSI_INIT_TIMEOUT_MS);
do {