Re: [PATCH 4/4] libata: Fall back to unqueued READ LOG EXT if the DMA variant fails

[Hannes Reinecke <hare@suse.de>]

On 05/05/2015 03:54 AM, Martin K. Petersen wrote:
> Some devices advertise support for the READ/WRITE LOG DMA EXT commands
> but fail when we try to issue them. This can lead to queued TRIM being
> unintentionally disabled since the relevant feature flag is located in a
> general purpose log page.
> 
> Fall back to unqueued READ LOG EXT if the DMA variant fails while
> reading a log page.
> 
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> ---
>  drivers/ata/libata-eh.c | 12 +++++++++++-
>  include/linux/libata.h  |  1 +
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> index 07f41be38fbe..2893563d0537 100644
> --- a/drivers/ata/libata-eh.c
> +++ b/drivers/ata/libata-eh.c
> @@ -1507,13 +1507,17 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
>  {
>  	struct ata_taskfile tf;
>  	unsigned int err_mask;
> +	bool dma = false;
>  
>  	DPRINTK("read log page - log 0x%x, page 0x%x\n", log, page);
>  
> +retry:
>  	ata_tf_init(dev, &tf);
> -	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id)) {
> +	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id) &&
> +	    !(dev->horkage & ATA_HORKAGE_NO_NCQ_LOG)) {
>  		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
>  		tf.protocol = ATA_PROT_DMA;
> +		dma = true;
>  	} else {
>  		tf.command = ATA_CMD_READ_LOG_EXT;
>  		tf.protocol = ATA_PROT_PIO;
> @@ -1527,6 +1531,12 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
>  	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
>  				     buf, sectors * ATA_SECT_SIZE, 0);
>  
> +	if (err_mask && dma) {
> +		dev->horkage |= ATA_HORKAGE_NO_NCQ_LOG;
> +		ata_dev_warn(dev, "READ LOG DMA EXT failed, trying unqueued\n");
> +		goto retry;
> +	}
> +
>  	DPRINTK("EXIT, err_mask=%x\n", err_mask);
>  	return err_mask;
>  }
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index 8dad4a307bb8..c3ef58014b33 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -424,6 +424,7 @@ enum {
>  	ATA_HORKAGE_NOLPM	= (1 << 20),	/* don't use LPM */
>  	ATA_HORKAGE_WD_BROKEN_LPM = (1 << 21),	/* some WDs have broken LPM */
>  	ATA_HORKAGE_ZERO_AFTER_TRIM = (1 << 22),/* guarantees zero after trim */
> +	ATA_HORKAGE_NO_NCQ_LOG	= (1 << 23),	/* don't use NCQ for log read */
>  
>  	 /* DMA mask for user DMA control: User visible values; DO NOT
>  	    renumber */
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes

-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@suse.de			               +49 911 74053 688
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