Re: [PATCH] libata: fix checking of DMA state

From: Paul Menzel <pmenzel@molgen.mpg.de>
To: "Reimar Döffinger" <Reimar.Doeffinger@gmx.de>
Cc: Damien Le Moal <Damien.LeMoal@wdc.com>,
	linux-ide@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] libata: fix checking of DMA state
Date: Mon, 27 Sep 2021 10:56:34 +0200	[thread overview]
Message-ID: <3850840f-ea01-a297-9347-55e8b5bac221@molgen.mpg.de> (raw)
In-Reply-To: <20210819081340.4362-1-Reimar.Doeffinger@gmx.de>

Dear Reimar,

Thank you for the patch.

Am 19.08.21 um 10:13 schrieb Reimar Döffinger:

Maybe start with a problem statement:

With some SSDs Linux logs the error below:

     failed to set xfermode (err_mask=0x40)

> Checking if DMA is enabled should be done via the
> ata_dma_enabled helper function, since the init state
> 0xff indicates disabled.
> Only the libata-core logic is tested on actual devices,
> the other changes are based on code review only.

Your Signed-off-by line is missing, and you might want to add the Linux 
kernel bug tracker entry:

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=195895

> ---
> Changes to previous version:
> - removed initialization change for SATA. I got confused by the
>    ping-pong between libata-eh and libata-core and thought SATA did not
>    set up xfermode
> - reviewed other cases that used dma_mode in boolean context and those
>    seemed to need changing as well, so added them to patch.
>    I did not see any places that would set dma_mode to 0 ever, so I
>    do think they were all indeed wrong.
> 
>   drivers/ata/libata-core.c  | 2 +-
>   drivers/ata/libata-scsi.c  | 4 ++--
>   drivers/ata/pata_ali.c     | 2 +-
>   drivers/ata/pata_optidma.c | 4 ++--
>   drivers/ata/pata_radisys.c | 2 +-
>   5 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 9934f6c465f4..52469b39d424 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -2004,7 +2004,7 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
>   
>   retry:
>   	ata_tf_init(dev, &tf);
> -	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id) &&
> +	if (ata_dma_enabled(dev) && ata_id_has_read_log_dma_ext(dev->id) &&
>   	    !(dev->horkage & ATA_HORKAGE_NO_DMA_LOG)) {
>   		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
>   		tf.protocol = ATA_PROT_DMA;
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index b9588c52815d..9e51251161e9 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3023,7 +3023,7 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
>   	ata_qc_set_pc_nbytes(qc);
>   
>   	/* We may not issue DMA commands if no DMA mode is set */
> -	if (tf->protocol == ATA_PROT_DMA && dev->dma_mode == 0) {
> +	if (tf->protocol == ATA_PROT_DMA && !ata_dma_enabled(dev)) {
>   		fp = 1;
>   		goto invalid_fld;
>   	}
> @@ -3173,7 +3173,7 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
>   	u8 unmap = cdb[1] & 0x8;
>   
>   	/* we may not issue DMA commands if no DMA mode is set */
> -	if (unlikely(!dev->dma_mode))
> +	if (unlikely(!ata_dma_enabled(dev)))
>   		goto invalid_opcode;
>   
>   	/*
> diff --git a/drivers/ata/pata_ali.c b/drivers/ata/pata_ali.c
> index 557ecf466102..28b56811306f 100644
> --- a/drivers/ata/pata_ali.c
> +++ b/drivers/ata/pata_ali.c
> @@ -215,7 +215,7 @@ static void ali_set_piomode(struct ata_port *ap, struct ata_device *adev)
>   		struct ata_timing p;
>   		ata_timing_compute(pair, pair->pio_mode, &p, T, 1);
>   		ata_timing_merge(&p, &t, &t, ATA_TIMING_SETUP|ATA_TIMING_8BIT);
> -		if (pair->dma_mode) {
> +		if (ata_dma_enabled(pair)) {
>   			ata_timing_compute(pair, pair->dma_mode, &p, T, 1);
>   			ata_timing_merge(&p, &t, &t, ATA_TIMING_SETUP|ATA_TIMING_8BIT);
>   		}
> diff --git a/drivers/ata/pata_optidma.c b/drivers/ata/pata_optidma.c
> index f6278d9de348..ad1090b90e52 100644
> --- a/drivers/ata/pata_optidma.c
> +++ b/drivers/ata/pata_optidma.c
> @@ -153,7 +153,7 @@ static void optidma_mode_setup(struct ata_port *ap, struct ata_device *adev, u8
>   	if (pair) {
>   		u8 pair_addr;
>   		/* Hardware constraint */
> -		if (pair->dma_mode)
> +		if (ata_dma_enabled(pair))
>   			pair_addr = 0;
>   		else
>   			pair_addr = addr_timing[pci_clock][pair->pio_mode - XFER_PIO_0];
> @@ -301,7 +301,7 @@ static u8 optidma_make_bits43(struct ata_device *adev)
>   	};
>   	if (!ata_dev_enabled(adev))
>   		return 0;
> -	if (adev->dma_mode)
> +	if (ata_dma_enabled(adev))
>   		return adev->dma_mode - XFER_MW_DMA_0;
>   	return bits43[adev->pio_mode - XFER_PIO_0];
>   }
> diff --git a/drivers/ata/pata_radisys.c b/drivers/ata/pata_radisys.c
> index 8fde4a86401b..626b14f0f2ea 100644
> --- a/drivers/ata/pata_radisys.c
> +++ b/drivers/ata/pata_radisys.c
> @@ -173,7 +173,7 @@ static unsigned int radisys_qc_issue(struct ata_queued_cmd *qc)
>   	if (adev != ap->private_data) {
>   		/* UDMA timing is not shared */
>   		if (adev->dma_mode < XFER_UDMA_0) {
> -			if (adev->dma_mode)
> +			if (ata_dma_enabled(adev))
>   				radisys_set_dmamode(ap, adev);
>   			else if (adev->pio_mode)
>   				radisys_set_piomode(ap, adev);
> 

I am sorry, it took me so long to test this.

Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>

(MSI B350M MORTAR with a M.2 Crucial MX500 SSD (SATA/AHCI, 
CT1000MX500SSD4, M3CR020))

Kind regards,

Paul