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USB: usb-storage: use adaptive DMA mask
This patch (as1060) makes usb-storage set the DMA alignment mask for SCSI slaves to match the maxpacket size of the bulk-IN endpoint, rather than always setting it to 511. For full-speed devices that mask is too restrictive, and wireless USB devices can have maxpacket sizes larger than 512. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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1 changed files with 8 additions and 6 deletions
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@ -73,6 +73,7 @@ static const char* host_info(struct Scsi_Host *host)
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static int slave_alloc (struct scsi_device *sdev)
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static int slave_alloc (struct scsi_device *sdev)
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{
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{
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struct us_data *us = host_to_us(sdev->host);
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struct us_data *us = host_to_us(sdev->host);
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struct usb_host_endpoint *bulk_in_ep;
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/*
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/*
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* Set the INQUIRY transfer length to 36. We don't use any of
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* Set the INQUIRY transfer length to 36. We don't use any of
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@ -84,12 +85,13 @@ static int slave_alloc (struct scsi_device *sdev)
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/* Scatter-gather buffers (all but the last) must have a length
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/* Scatter-gather buffers (all but the last) must have a length
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* divisible by the bulk maxpacket size. Otherwise a data packet
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* divisible by the bulk maxpacket size. Otherwise a data packet
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* would end up being short, causing a premature end to the data
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* would end up being short, causing a premature end to the data
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* transfer. Since high-speed bulk pipes have a maxpacket size
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* transfer. We'll use the maxpacket value of the bulk-IN pipe
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* of 512, we'll use that as the scsi device queue's DMA alignment
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* to set the SCSI device queue's DMA alignment mask.
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* mask. Guaranteeing proper alignment of the first buffer will
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*/
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* have the desired effect because, except at the beginning and
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bulk_in_ep = us->pusb_dev->ep_in[usb_pipeendpoint(us->recv_bulk_pipe)];
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* the end, scatter-gather buffers follow page boundaries. */
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blk_queue_update_dma_alignment(sdev->request_queue,
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blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
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le16_to_cpu(bulk_in_ep->desc.wMaxPacketSize) - 1);
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/* wMaxPacketSize must be a power of 2 */
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/*
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/*
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* The UFI spec treates the Peripheral Qualifier bits in an
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* The UFI spec treates the Peripheral Qualifier bits in an
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