linux-kernel - Re: [PATCH v1 03/23] ata: sata_dwc_460ex: set dma

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Message-ID: <571A235C.5070007@cogentembedded.com>
Date:	Fri, 22 Apr 2016 16:13:00 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Tejun Heo <tj@...nel.org>, linux-ide@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Christian Lamparter <chunkeey@...glemail.com>,
	Måns Rullgård <mans@...sr.com>,
	Julian Margetson <runaway@...dw.ms>
Subject: Re: [PATCH v1 03/23] ata: sata_dwc_460ex: set dma_boundary to 0x1fff

Hello.

On 04/21/2016 09:15 PM, Andy Shevchenko wrote:

> The original code states:
>
> 	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.
>
> Since we have switched to generic DMAengine API we satisfy above by setting
> dma_boundary value to 0x1fff.
>
> Suggested-by: Mans Rullgard <mans@...sr.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>   drivers/ata/sata_dwc_460ex.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> 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 */,

    Not ~0x1fff?

[...]

MBR, Sergei