Re: [PATCH] pata_it821x: sync with IDE it821x driver

[Tejun Heo <htejun@gmail.com>]

Hello,

Bartlomiej Zolnierkiewicz wrote:
> * (partially) fix DMA in RAID mode
> 
>   Code intended to check DMA status was checking DMA command register.
>   Moreover firmware seems to "forget" to set DMA capable bit for the
>   slave device (at least in RAID mode but without ITE RAID volumes) so
>   check device ID for DMA capable bit when deciding whether to use DMA
>   and remove DMA status check completely.
> 
>   Thanks to Pavol Šimo for the bugreport and testing the initial fix.

Ah... This is the mysterious mwdma configuration in smart mode, right?
Thanks for fixing this.

>   This change unfortunately still doesn't fix DMA in RAID mode (which
>   works fine with IDE it821x) but Alan is working on the missing pieces
>   (pata_it821x vs libata EH issues).

This is the lbal/nsect SRST problem, right?

> @@ -258,8 +259,14 @@ static void it821x_passthru_set_piomode(
>  	static const u8 pio_want[]    = { ATA_66, ATA_66, ATA_66, ATA_66, ATA_ANY };
>  
>  	struct it821x_dev *itdev = ap->private_data;
> +	struct ata_device *pair = ata_dev_pair(adev);
>  	int unit = adev->devno;
> -	int mode_wanted = adev->pio_mode - XFER_PIO_0;
> +	int mode_wanted = adev->pio_mode;
> +
> +	if (pair && adev->pio_mode > pair->pio_mode)
> +		mode_wanted = pair->pio_mode;
> +
> +	mode_wanted -= XFER_PIO_0;

I think this is better done by mode_filter callback which is guaranteed
to be called before any actual mode configuration is performed and in
device order (master then slave).

Thanks.

-- 
tejun