linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: Mark Brown <broonie@kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	bcm-kernel-feedback-list@broadcom.com,
	Eric Anholt <eric@anholt.net>,
	Stefan Wahren <stefan.wahren@i2se.com>
Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] spi: bcm2835: only split transfers that exceed DLEN if DMA available
Date: Thu,  9 May 2019 16:39:59 +0200	[thread overview]
Message-ID: <20190509144000.681-1-nsaenzjulienne@suse.de> (raw)

There is no use for this when performing non DMA operations. So we
bypass the split.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/spi/spi-bcm2835.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 37893313e595..649fd6caed35 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -861,15 +861,17 @@ static int bcm2835_spi_prepare_message(struct spi_master *master,
 	u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
 	int ret;
 
-	/*
-	 * DMA transfers are limited to 16 bit (0 to 65535 bytes) by the SPI HW
-	 * due to DLEN. Split up transfers (32-bit FIFO aligned) if the limit is
-	 * exceeded.
-	 */
-	ret = spi_split_transfers_maxsize(master, msg, 65532,
-					  GFP_KERNEL | GFP_DMA);
-	if (ret)
-		return ret;
+	if (master->can_dma) {
+		/*
+		 * DMA transfers are limited to 16 bit (0 to 65535 bytes) by
+		 * the SPI HW due to DLEN. Split up transfers (32-bit FIFO
+		 * aligned) if the limit is exceeded.
+		 */
+		ret = spi_split_transfers_maxsize(master, msg, 65532,
+						  GFP_KERNEL | GFP_DMA);
+		if (ret)
+			return ret;
+	}
 
 	cs &= ~(BCM2835_SPI_CS_CPOL | BCM2835_SPI_CS_CPHA);
 
-- 
2.21.0


             reply	other threads:[~2019-05-09 14:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-09 14:39 Nicolas Saenz Julienne [this message]
2019-05-13 12:31 ` Applied "spi: bcm2835: only split transfers that exceed DLEN if DMA available" to the spi tree Mark Brown

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190509144000.681-1-nsaenzjulienne@suse.de \
    --to=nsaenzjulienne@suse.de \
    --cc=bcm-kernel-feedback-list@broadcom.com \
    --cc=broonie@kernel.org \
    --cc=eric@anholt.net \
    --cc=f.fainelli@gmail.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rpi-kernel@lists.infradead.org \
    --cc=linux-spi@vger.kernel.org \
    --cc=rjui@broadcom.com \
    --cc=sbranden@broadcom.com \
    --cc=stefan.wahren@i2se.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).