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| Started by | Tejun Heo <tj@kernel.org> |
|---|---|
| First post | 2016-05-08 21:50 +0200 |
| Last post | 2016-05-08 23:40 +0200 |
| Articles | 2 — 2 participants |
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Re: [PATCH v2 03/23] ata: sata_dwc_460ex: set dma_boundary to 0x1fff Tejun Heo <tj@kernel.org> - 2016-05-08 21:50 +0200
Re: [PATCH v2 03/23] ata: sata_dwc_460ex: set dma_boundary to 0x1fff Måns Rullgård <mans@mansr.com> - 2016-05-08 23:40 +0200
| From | Tejun Heo <tj@kernel.org> |
|---|---|
| Date | 2016-05-08 21:50 +0200 |
| Subject | Re: [PATCH v2 03/23] ata: sata_dwc_460ex: set dma_boundary to 0x1fff |
| Message-ID | <rwCSd-4xB-5@gated-at.bofh.it> |
On Tue, Apr 26, 2016 at 12:03:04PM +0300, Andy Shevchenko wrote:
> diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
> index 7f95389..aee8873 100644
> --- a/drivers/ata/sata_dwc_460ex.c
> +++ b/drivers/ata/sata_dwc_460ex.c
> @@ -1151,7 +1151,13 @@ static struct scsi_host_template sata_dwc_sht = {
> */
> .sg_tablesize = LIBATA_MAX_PRD,
> /* .can_queue = ATA_MAX_QUEUE, */
> - .dma_boundary = ATA_DMA_BOUNDARY,
> + /*
> + * Make sure a LLI block is not created that will span 8K max FIS
> + * boundary. If the block spans such a FIS boundary, there is a chance
> + * that a DMA burst will cross that boundary -- this results in an
> + * error in the host controller.
> + */
> + .dma_boundary = 0x1fff /* ATA_DMA_BOUNDARY */,
The host controller can't cross 8k boundary? Is this for real?
--
tejun
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| From | Måns Rullgård <mans@mansr.com> |
|---|---|
| Date | 2016-05-08 23:40 +0200 |
| Message-ID | <rwEAF-6mD-3@gated-at.bofh.it> |
| In reply to | #1396481 |
Tejun Heo <tj@kernel.org> writes:
> On Tue, Apr 26, 2016 at 12:03:04PM +0300, Andy Shevchenko wrote:
>> diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
>> index 7f95389..aee8873 100644
>> --- a/drivers/ata/sata_dwc_460ex.c
>> +++ b/drivers/ata/sata_dwc_460ex.c
>> @@ -1151,7 +1151,13 @@ static struct scsi_host_template sata_dwc_sht = {
>> */
>> .sg_tablesize = LIBATA_MAX_PRD,
>> /* .can_queue = ATA_MAX_QUEUE, */
>> - .dma_boundary = ATA_DMA_BOUNDARY,
>> + /*
>> + * Make sure a LLI block is not created that will span 8K max FIS
>> + * boundary. If the block spans such a FIS boundary, there is a chance
>> + * that a DMA burst will cross that boundary -- this results in an
>> + * error in the host controller.
>> + */
>> + .dma_boundary = 0x1fff /* ATA_DMA_BOUNDARY */,
>
> The host controller can't cross 8k boundary? Is this for real?
From the manual:
DMA block and burst transaction sizes are critical for DMA operation.
(Also see the definition of "DMA transfer".) These sizes should be
selected properly to ensure error-free bus transfers. It is required
that the DMA write burst transfer does not cross the 8192-byte Data
FIS boundary, because the Transport Layer maintains the DMA state for
the duration of the Data FIS transmission.
--
Måns Rullgård
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