Hi,
I got this email from a mailing list somewhere. I'm experiencing an
issue where I'm unable to flash using spidev on a Raspberry Pi.
I'm running "4.14.79-1.rpi.fc27.armv7hl", which is based on Fedberry.
I'm experiencing two issues:
1) I'm completely unable to access any SPI chips. This appears to be
due to a bug in the kernel driver, which always yanks the CS line high
despite the cs_change set to 0. A workaround I've come up with is to do
everything as a single transaction, which seems to fix the problem on my
device:
diff --git a/linux_spi.c b/linux_spi.c
index 3e60492..50f8220 100644
--- a/linux_spi.c
+++ b/linux_spi.c
@@ -183,14 +183,12 @@ static int linux_spi_send_command(struct flashctx
*flash, unsigned int writecnt,
unsigned char *rxbuf)
{
int iocontrol_code;
+ char tmp_buf[readcnt + writecnt];
struct spi_ioc_transfer msg[2] = {
{
.tx_buf = (uint64_t)(uintptr_t)txbuf,
- .len = writecnt,
- },
- {
- .rx_buf = (uint64_t)(uintptr_t)rxbuf,
- .len = readcnt,
+ .rx_buf = (uint64_t)(uintptr_t)tmp_buf,
+ .len = writecnt+readcnt,
},
};
@@ -203,15 +201,14 @@ static int linux_spi_send_command(struct flashctx
*flash, unsigned int writecnt,
/* Just submit the first (write) request in case there is
nothing
to read. Otherwise submit both requests. */
- if (readcnt == 0)
- iocontrol_code = SPI_IOC_MESSAGE(1);
- else
- iocontrol_code = SPI_IOC_MESSAGE(2);
+ iocontrol_code = SPI_IOC_MESSAGE(1);
if (ioctl(fd, iocontrol_code, msg) == -1) {
msg_cerr("%s: ioctl: %s\n", __func__, strerror(errno));
return -1;
}
+
+ memcpy(rxbuf, tmp_buf + writecnt, readcnt);
return 0;
}
-------------------
2) The other issue is that my device appears to want SPI_MODE_1. When I
set SPI_MODE_1, it is able to detect and program the board, but fails to
verify. The image that gets loaded still works, but I'm unsure of
what's causing the issue.
I can do some more debugging, but changing SPI_MODE_1 and applying the
above-mentioned patch solves the issue for me.
Sean
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