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List: linux-ide
Subject: Re: [PATCH] libata: fix setting and checking of DMA state.
From: Damien Le Moal <Damien.LeMoal () wdc ! com>
Date: 2021-08-18 23:30:48
Message-ID: DM6PR04MB7081AB7034F116CDFBA43890E7FF9 () DM6PR04MB7081 ! namprd04 ! prod ! outlook ! com
[Download RAW message or body]
On 2021/08/18 4:03, Reimar Döffinger wrote:
> Checking if DMA is enabled should be done via the
> ata_dma_enabled helper function.
> Update dma_mode initialization so that SATA devices
> are reported as DMA enabled.
Please drop the period at the end of the patch title
> ---
> drivers/ata/libata-core.c | 4 ++--
> include/linux/ata.h | 1 +
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 9934f6c465f4..a5fe20bb22d6 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) &&
This change is OK I think. Note that there are many other places where
dev->dma_mode is testing directly. It may be good to check those too.
> !(dev->horkage & ATA_HORKAGE_NO_DMA_LOG)) {
> tf.command = ATA_CMD_READ_LOG_DMA_EXT;
> tf.protocol = ATA_PROT_DMA;
> @@ -2824,7 +2824,7 @@ int ata_bus_probe(struct ata_port *ap)
> * bus as we may be talking too fast.
> */
> dev->pio_mode = XFER_PIO_0;
> - dev->dma_mode = 0xff;
> + dev->dma_mode = ap->flags & ATA_FLAG_SATA ? XFER_SATA : 0xff;
This however is not OK I think. You are setting a transfer speed without going
through the link speed negotiation.
>
> /* If the controller has a pio mode setup function
> * then use it to set the chipset to rights. Don't
> diff --git a/include/linux/ata.h b/include/linux/ata.h
> index 1b44f40c7700..7bb2c2acbc42 100644
> --- a/include/linux/ata.h
> +++ b/include/linux/ata.h
> @@ -374,6 +374,7 @@ enum {
>
> /* SETFEATURES stuff */
> SETFEATURES_XFER = 0x03,
> + XFER_SATA = 0x48,
Where does this come from ?
> XFER_UDMA_7 = 0x47,
> XFER_UDMA_6 = 0x46,
> XFER_UDMA_5 = 0x45,
>
--
Damien Le Moal
Western Digital Research
=
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