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From: Jeff Epler <jepler@unpythonic.net>
To: linux-rt-users@vger.kernel.org
Subject: [PATCH 3/4] spidev: actually use synchronous transfers
Date: Mon,  1 Sep 2014 09:30:34 -0500	[thread overview]
Message-ID: <1409581835-70814-4-git-send-email-jepler@unpythonic.net> (raw)
In-Reply-To: <1409581835-70814-1-git-send-email-jepler@unpythonic.net>

this reduces a source of latency
---
 drivers/spi/spidev.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index dda7632..6e37c59 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -120,15 +120,9 @@ spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 	if (spidev->spi == NULL)
 		status = -ESHUTDOWN;
 	else
-		status = spi_async(spidev->spi, message);
+		status = spi_sync(spidev->spi, message);
 	spin_unlock_irq(&spidev->spi_lock);
 
-	if (status == 0) {
-		wait_for_completion(&done);
-		status = message->status;
-		if (status == 0)
-			status = message->actual_length;
-	}
 	return status;
 }
 
-- 
2.0.1


  parent reply	other threads:[~2014-09-01 15:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-01 14:30 [RFC 0/4] Improving SPI driver latency (vs v3.8.13.14-rt31) Jeff Epler
2014-09-01 14:30 ` [PATCH 1/4] spi: reenable sync SPI transfers Jeff Epler
2014-09-01 14:30 ` [PATCH 2/4] spidev: Avoid runtime memory allocations Jeff Epler
2014-09-01 14:30 ` Jeff Epler [this message]
2014-09-01 14:30 ` [PATCH 4/4] spidev-s3c64xx: allocate dma channel at startup Jeff Epler
2014-09-01 15:41 ` [RFC 0/4] Improving SPI driver latency (vs v3.8.13.14-rt31) Philipp Lutz
2014-09-01 18:13   ` Jeff Epler
2014-09-01 22:30     ` Harry van Haaren
2014-09-09 20:01 ` Uwe Kleine-König

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