From: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> To: Gerhard Sittig <gsi-ynQEQJNshbs@public.gmane.org> Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linaro-kernel-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Subject: [PATCH] spi: Fix handling of cs_change in core implementation Date: Sun, 30 Mar 2014 00:27:45 +0000 [thread overview] Message-ID: <1396139265-28900-1-git-send-email-broonie@kernel.org> (raw) From: Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> The core implementation of cs_change didn't follow the documentation which says that cs_change in the middle of the transfer means to briefly deassert chip select, instead it followed buggy drivers which change the polarity of chip select. Use a delay of 10us between deassert and reassert simply from pulling numbers out of a hat. Reported-by: Gerhard Sittig <gsi-ynQEQJNshbs@public.gmane.org> Signed-off-by: Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> --- Compile tested only. drivers/spi/spi.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 121c43b..4eb9bf0 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -754,7 +754,6 @@ static int spi_transfer_one_message(struct spi_master *master, struct spi_message *msg) { struct spi_transfer *xfer; - bool cur_cs = true; bool keep_cs = false; int ret = 0; int ms = 1; @@ -800,8 +799,9 @@ static int spi_transfer_one_message(struct spi_master *master, &msg->transfers)) { keep_cs = true; } else { - cur_cs = !cur_cs; - spi_set_cs(msg->spi, cur_cs); + spi_set_cs(msg->spi, false); + udelay(10); + spi_set_cs(msg->spi, true); } } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next reply other threads:[~2014-03-30 0:27 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-03-30 0:27 Mark Brown [this message] [not found] ` <1396139265-28900-1-git-send-email-broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2014-03-31 7:45 ` Gerhard Sittig [not found] ` <20140331074529.GE2775-kDjWylLy9wD0K7fsECOQyeGNnDKD8DIp@public.gmane.org> 2014-03-31 17:17 ` Mark Brown
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