Anastasia Klimchuk submitted this change.
serial: Fix sp_flush_incoming for serprog TCP connections
During the development of an esp32 serprog-compatible SPI programmer,
and implementation of the TCP over Wi-Fi for serprog,
I discovered that sp_flush_incoming() silently fails
if the underlying sp_fd descriptor is a TCP socket.
This patch adds a check for this case - tcflush returns ENOTTY,
meaning tcflush is not supported for not terminal objects,
in this case a fallback serialport_read_nonblock loop is used.
TESTED=esp32-serprog, TCP-over-WiFi mode, ~90% connection attempts fail to synchronize without patch; no synchronization issues with patch applied.
Signed-off-by: Stanislav Ponomarev <me@stasponomarev.com>
Change-Id: I9724a2fcd4a41dede2c15f83877efa6c3b0b7fae
Reviewed-on: https://review.coreboot.org/c/flashrom/+/79112
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
---
M serial.c
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/serial.c b/serial.c
index 10d739a..577ccf4 100644
--- a/serial.c
+++ b/serial.c
@@ -377,10 +377,26 @@
#if IS_WINDOWS
PurgeComm(sp_fd, PURGE_RXCLEAR);
#else
- /* FIXME: error handling */
- tcflush(sp_fd, TCIFLUSH);
+ if (!tcflush(sp_fd, TCIFLUSH))
+ return;
+
+ if (errno == ENOTTY) { // TCP socket case: sp_fd is not a terminal descriptor - tcflush is not supported
+ unsigned char c;
+ int ret;
+
+ do {
+ ret = serialport_read_nonblock(&c, 1, 1, NULL);
+ } while (ret == 0);
+
+ // positive error code indicates no data available immediately - similar to EAGAIN/EWOULDBLOCK
+ // i.e. all buffered data was read
+ // negative error code indicates a permanent error
+ if (ret < 0)
+ msg_perr("Could not flush serial port incoming buffer: read has failed");
+ } else { // any other errno indicates an unrecoverable sp_fd state
+ msg_perr_strerror("Could not flush serial port incoming buffer: ");
+ }
#endif
- return;
}
int serialport_shutdown(void *data)
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