Messages in this thread | | | Date | Sat, 13 Jul 2013 03:08:27 +0400 | From | Sergei Shtylyov <> | Subject | Re: [RFC/RFT PATCH 3/5] scsi: Use dma_max_pfn(dev) helper for bounce_limit calculations |
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Hello.
On 07/13/2013 02:25 AM, Russell King - ARM Linux wrote:
>>> DMA bounce limit is the maximum direct DMA'able memory beyond which >>> bounce buffers has to be used to perform dma operations. SCSI driver >>> relies on dma_mask but its calculation is based on max_*pfn which >>> don't have uniform meaning across architectures. So make use of >>> dma_max_pfn() which is expected to return the DMAable maximum pfn >>> value across architectures.
>>> Cc: Russell King <linux@arm.linux.org.uk> >>> Cc: linux-scsi@vger.kernel.org
>>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> >>> --- >>> drivers/scsi/scsi_lib.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >>> index 86d5220..e8275fa 100644 >>> --- a/drivers/scsi/scsi_lib.c >>> +++ b/drivers/scsi/scsi_lib.c >>> @@ -1668,7 +1668,7 @@ u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) >>> >>> host_dev = scsi_get_device(shost); >>> if (host_dev && host_dev->dma_mask) >>> - bounce_limit = *host_dev->dma_mask; >>> + bounce_limit = dma_max_pfn(host_dev) << PAGE_SHIFT;
>> You definitely forgot -1 here.
> Please explain your point.
Previously, 'bounce_limit' would look like 0xffffffff (unless I'm mistaken), now it would look like 0xfffff000 which is hardly what we're looking for, no?
WBR, Sergei
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