usb-storage: stop using block layer bounce buffers

From: Christoph Hellwig <hch@lst.de>
To: stern@rowland.harvard.edu
Cc: linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net,
	linux-scsi@vger.kernel.org
Subject: usb-storage: stop using block layer bounce buffers
Date: Sun, 15 Apr 2018 16:53:29 +0200	[thread overview]
Message-ID: <20180415145329.855-1-hch@lst.de> (raw)

USB host controllers now must handle highmem, so we can get rid of bounce
buffering highmem pages in the block layer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/usb/storage/scsiglue.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index c267f2812a04..4e453d9d45d5 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -130,15 +130,6 @@ static int slave_configure(struct scsi_device *sdev)
 		blk_queue_max_hw_sectors(sdev->request_queue, 2048);
 	}
 
-	/*
-	 * Some USB host controllers can't do DMA; they have to use PIO.
-	 * They indicate this by setting their dma_mask to NULL.  For
-	 * such controllers we need to make sure the block layer sets
-	 * up bounce buffers in addressable memory.
-	 */
-	if (!us->pusb_dev->bus->controller->dma_mask)
-		blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);
-
 	/*
 	 * We can't put these settings in slave_alloc() because that gets
 	 * called before the device type is known.  Consequently these
