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* [PATCH v2] spi: Setup the master controller driver before setting the chipselect
@ 2015-10-16 15:29 Franklin S Cooper Jr
  2015-10-16 15:45 ` Andy Shevchenko
  0 siblings, 1 reply; 8+ messages in thread
From: Franklin S Cooper Jr @ 2015-10-16 15:29 UTC (permalink / raw)
  To: linux-kernel-u79uwXL29TY76Z2rM5mHXA,
	linux-spi-u79uwXL29TY76Z2rM5mHXA, broonie-DgEjT+Ai2ygdnm+yROfE0A,
	nsekhar-l0cyMroinI0, ssantosh-DgEjT+Ai2ygdnm+yROfE0A,
	iivanov-NEYub+7Iv8PQT0dZR+AlfA, m-karicheri2-l0cyMroinI0,
	iivanov.xz-Re5JQEeQqe8AvxtiuMwx3w,
	andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w,
	jarkko.nikula-VuQAYsv1563Yd54FQh9/CA,
	hkallweit1-Re5JQEeQqe8AvxtiuMwx3w
  Cc: Franklin S Cooper Jr

SPI controllers may need to be properly setup before chip selects
can be used. Therefore, wait until the spi controller has a chance
to perform their setup procedure before trying to use the chip
select.

This also insures that the chip selects pins are in a good
state before asseting them which otherwise may cause confusion.

Signed-off-by: Franklin S Cooper Jr <fcooper-l0cyMroinI0@public.gmane.org>
---
Keystone 2 devices currently fail to boot in linux-next after the
below commit was applied:

spi: bitbang: switch to the generic implementation of transfer_one_message
commit: 0037686596832572bbca05ab168d9884d7d704c1

This patch allows Keystone 2 devices to boot again in linux-next.

Tested this patch on K2E evm and am437 starterkit which both have SPI
devices to insure regressions aren't seen.

V2 Changes:
Update commit message.

 drivers/spi/spi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4c638f3..9d5525a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2059,11 +2059,11 @@ int spi_setup(struct spi_device *spi)
 	if (!spi->max_speed_hz)
 		spi->max_speed_hz = spi->master->max_speed_hz;
 
-	spi_set_cs(spi, false);
-
 	if (spi->master->setup)
 		status = spi->master->setup(spi);
 
+	spi_set_cs(spi, false);
+
 	dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
 			(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
 			(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
-- 
2.6.1

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^ permalink raw reply related	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2015-10-28  0:33 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-10-16 15:29 [PATCH v2] spi: Setup the master controller driver before setting the chipselect Franklin S Cooper Jr
2015-10-16 15:45 ` Andy Shevchenko
2015-10-16 15:47   ` Franklin S Cooper Jr.
2015-10-16 15:55     ` Andy Shevchenko
     [not found]       ` <CAHp75VchYayRsvsjPoM9YphcjMajfvYuDrLcLrTiADVn8LU=8A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-10-27 12:22         ` Franklin S Cooper Jr.
     [not found]           ` <562F6C9B.6010607-l0cyMroinI0@public.gmane.org>
2015-10-27 13:11             ` Grygorii Strashko
     [not found]               ` <562F7801.3090508-l0cyMroinI0@public.gmane.org>
2015-10-27 13:34                 ` Grygorii Strashko
2015-10-28  0:33             ` Mark Brown

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