| Message ID | 1444636322-6772-1-git-send-email-vigneshr@ti.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | bc27a53928981662079aa243915b443370294a03 |
| Headers | show |
diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c index aa6d284131e0..81b84858cfee 100644 --- a/drivers/spi/spi-ti-qspi.c +++ b/drivers/spi/spi-ti-qspi.c @@ -410,11 +410,10 @@ static int ti_qspi_start_transfer_one(struct spi_master *master, mutex_unlock(&qspi->list_lock); + ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG); m->status = status; spi_finalize_current_message(master); - ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG); - return status; }
Writing invalid command to QSPI_SPI_CMD_REG will terminate current transfer and de-assert the chip select. This has to be done before calling spi_finalize_current_message(). Because spi_finalize_current_message() will mark the end of current message transfer and schedule the next transfer. If the chipselect is not de-asserted before calling spi_finalize_current_message() then the next transfer will overlap with the previous transfer leading to data corruption. __spi_pump_message() can be called either from kthread worker context or directly from the calling process's context. It is possible that these two calls can race against each other. But race is serialized by checking whether master->cur_msg == NULL (pointer to msg being handled by transfer_one() at present). The master->cur_msg is set to NULL when spi_finalize_current_message() is called on that message, which means calling spi_finalize_current_message() allows __spi_sync() to pump next message in calling process context. Now if spi-ti-qspi calls spi_finalize_current_message() before we terminate transfer at hardware side, if __spi_pump_message() is called from process context then the successive transactions can overlap. Fix this by moving writing invalid command to QSPI_SPI_CMD_REG to before calling spi_finalize_current_message() call. Cc: stable@vger.kernel.org # v3.12+ Signed-off-by: Vignesh R <vigneshr@ti.com> --- drivers/spi/spi-ti-qspi.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)