[nuttx] branch master updated: driver/spi: avoid calling QPOLL to change rx_length and cause data loss

[xiaoxiang]

This is an automated email from the ASF dual-hosted git repository.

xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/nuttx.git


The following commit(s) were added to refs/heads/master by this push:
     new dcb8188f07 driver/spi: avoid calling QPOLL to change rx_length and 
cause data loss
dcb8188f07 is described below

commit dcb8188f07fce41879d4cf8c9a666ad7c3c867f3
Author: dongjiuzhu1 <dongjiuz...@xiaomi.com>
AuthorDate: Tue Sep 5 19:20:46 2023 +0800

    driver/spi: avoid calling QPOLL to change rx_length and cause data loss
    
    When the application calls poll and returns the POLLIN event,
    QPOLL will be called again during the read operation,
    causing rx_length to change and data to be lost.
    Therefore, read only need to actively call qpoll to collect driver
    data when rx length is 0.
    
    Signed-off-by: dongjiuzhu1 <dongjiuz...@xiaomi.com>
---
 drivers/spi/spi_slave_driver.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi_slave_driver.c b/drivers/spi/spi_slave_driver.c
index ccc8f0dd3a..56ec300730 100644
--- a/drivers/spi/spi_slave_driver.c
+++ b/drivers/spi/spi_slave_driver.c
@@ -326,7 +326,7 @@ static ssize_t spi_slave_read(FAR struct file *filep, FAR 
char *buffer,
       return ret;
     }
 
-  do
+  while (priv->rx_length == 0)
     {
       remaining_words = SPIS_CTRLR_QPOLL(priv->ctrlr);
       if (remaining_words == 0)
@@ -360,11 +360,11 @@ static ssize_t spi_slave_read(FAR struct file *filep, FAR 
char *buffer,
             }
         }
     }
-  while (priv->rx_length == 0);
 
   read_bytes = MIN(buflen, priv->rx_length);
 
   memcpy(buffer, priv->rx_buffer, read_bytes);
+  priv->rx_length -= read_bytes;
 
   nxmutex_unlock(&priv->lock);
   return (ssize_t)read_bytes;