spi: stm32-qspi: Always wait BUSY bit to be cleared in stm32_qspi_wait_cmd()

spi: stm32-qspi: Always wait BUSY bit to be cleared in stm32_qspi_wait_cmd()

[patrice.chotard]

From: Patrice Chotard <patrice.chotard@foss.st.com>

In U-boot side, an issue has been encountered when QSPI source clock is
running at low frequency (24 MHz for example), waiting for TCF bit to be
set didn't ensure that all data has been send out the FIFO, we should also
wait that BUSY bit is cleared.

To prevent similar issue in kernel driver, we implement similar behavior
by always waiting BUSY bit to be cleared.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
---
 drivers/spi/spi-stm32-qspi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-stm32-qspi.c b/drivers/spi/spi-stm32-qspi.c
index 7e640ccc7e77..594f64136208 100644
--- a/drivers/spi/spi-stm32-qspi.c
+++ b/drivers/spi/spi-stm32-qspi.c
@@ -294,7 +294,7 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi,
 	int err = 0;
 
 	if (!op->data.nbytes)
-		return stm32_qspi_wait_nobusy(qspi);
+		goto wait_nobusy;
 
 	if (readl_relaxed(qspi->io_base + QSPI_SR) & SR_TCF)
 		goto out;
@@ -315,6 +315,9 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi,
 out:
 	/* clear flags */
 	writel_relaxed(FCR_CTCF | FCR_CTEF, qspi->io_base + QSPI_FCR);
+wait_nobusy:
+	if (!err)
+		err = stm32_qspi_wait_nobusy(qspi);
 
 	return err;
 }
-- 
2.17.1

Re: spi: stm32-qspi: Always wait BUSY bit to be cleared in stm32_qspi_wait_cmd()

[Mark Brown]

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On Thu, Jun 03, 2021 at 09:34:21AM +0200, patrice.chotard@foss.st.com wrote:
> From: Patrice Chotard <patrice.chotard@foss.st.com>
> 
> In U-boot side, an issue has been encountered when QSPI source clock is
> running at low frequency (24 MHz for example), waiting for TCF bit to be
> set didn't ensure that all data has been send out the FIFO, we should also
> wait that BUSY bit is cleared.

Please remember to put the [PATCH] in your subject.

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Re: spi: stm32-qspi: Always wait BUSY bit to be cleared in stm32_qspi_wait_cmd()

[Mark Brown]

On Thu, 3 Jun 2021 09:34:21 +0200, patrice.chotard@foss.st.com wrote:
> In U-boot side, an issue has been encountered when QSPI source clock is
> running at low frequency (24 MHz for example), waiting for TCF bit to be
> set didn't ensure that all data has been send out the FIFO, we should also
> wait that BUSY bit is cleared.
> 
> To prevent similar issue in kernel driver, we implement similar behavior
> by always waiting BUSY bit to be cleared.

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: stm32-qspi: Always wait BUSY bit to be cleared in stm32_qspi_wait_cmd()
      commit: d38fa9a155b2829b7e2cfcf8a4171b6dd3672808

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark