Re: [PATCH 14/15] ide: rework the code for selecting the best DMA transfer mode

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Bartlomiej Zolnierkiewicz wrote:
> [PATCH] ide: rework the code for selecting the best DMA transfer mode 

> Depends on the "ide: fix UDMA/MWDMA/SWDMA masks" patch.

   I'm now trying to rewrite hpt366.c to benefit more from these patches...
and alas, this very patch seems to be breaking filtering (at least) in this driver. :-]

> Index: b/drivers/ide/ide-dma.c
> ===================================================================
> --- a/drivers/ide/ide-dma.c
> +++ b/drivers/ide/ide-dma.c
> @@ -705,6 +705,80 @@ int ide_use_dma(ide_drive_t *drive)
>  
>  EXPORT_SYMBOL_GPL(ide_use_dma);
>  
> +static const u8 xfer_mode_bases[] = {
> +	XFER_UDMA_0,
> +	XFER_MW_DMA_0,
> +	XFER_SW_DMA_0,
> +};
> +
> +static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base)
> +{
> +	struct hd_driveid *id = drive->id;
> +	ide_hwif_t *hwif = drive->hwif;
> +	unsigned int mask = 0;
> +
> +	switch(base) {
> +	case XFER_UDMA_0:
> +		if ((id->field_valid & 4) == 0)
> +			break;
> +
> +		mask = id->dma_ultra & hwif->ultra_mask;
> +
> +		if (hwif->udma_filter)
> +			mask &= hwif->udma_filter(drive);
> +
> +		if ((mask & 0x78) && (eighty_ninty_three(drive) == 0))
> +			mask &= 0x07;

   Note the subtle difference between the old and new behavior: the old driver code was applying UltraDMA filter *after*
the cable type limit, and the new code does it *before*.

> +		break;
> +	case XFER_MW_DMA_0:
> +		mask = id->dma_mword & hwif->mwdma_mask;
> +		break;
> +	case XFER_SW_DMA_0:
> +		mask = id->dma_1word & hwif->swdma_mask;
> +		break;
> +	default:
> +		BUG();
> +		break;
> +	}
> +
> +	return mask;
> +}
> +
> +/**
> + *	ide_max_dma_mode	-	compute DMA speed
> + *	@drive: IDE device
> + *
> + *	Checks the drive capabilities and returns the speed to use
> + *	for the DMA transfer.  Returns 0 if the drive is incapable
> + *	of DMA transfers.
> + */
> +
> +u8 ide_max_dma_mode(ide_drive_t *drive)
> +{
> +	ide_hwif_t *hwif = drive->hwif;
> +	unsigned int mask;
> +	int x, i;
> +	u8 mode = 0;
> +
> +	if (drive->media != ide_disk && hwif->atapi_dma == 0)
> +		return 0;
> +
> +	for (i = 0; i < ARRAY_SIZE(xfer_mode_bases); i++) {
> +		mask = ide_get_mode_mask(drive, xfer_mode_bases[i]);
> +		x = fls(mask) - 1;
> +		if (x >= 0) {
> +			mode = xfer_mode_bases[i] + x;
> +			break;
> +		}
> +	}
> +
> +	printk(KERN_DEBUG "%s: selected mode 0x%x\n", drive->name, mode);
> +
> +	return mode;
> +}
> +
> +EXPORT_SYMBOL_GPL(ide_max_dma_mode);
> +
>  void ide_dma_verbose(ide_drive_t *drive)
>  {
>  	struct hd_driveid *id	= drive->id;
[...]
> Index: b/drivers/ide/pci/hpt366.c
> ===================================================================
> --- a/drivers/ide/pci/hpt366.c
> +++ b/drivers/ide/pci/hpt366.c
> @@ -513,43 +513,31 @@ static int check_in_drive_list(ide_drive
>  	return 0;
>  }
>  
> -static u8 hpt3xx_ratemask(ide_drive_t *drive)
> -{
> -	struct hpt_info *info	= pci_get_drvdata(HWIF(drive)->pci_dev);
> -	u8 mode			= info->max_mode;
> -
> -	if (!eighty_ninty_three(drive) && mode)
> -		mode = min(mode, (u8)1);
> -	return mode;
> -}
> -
>  /*
>   *	Note for the future; the SATA hpt37x we must set
>   *	either PIO or UDMA modes 0,4,5
>   */
> - 
> -static u8 hpt3xx_ratefilter(ide_drive_t *drive, u8 speed)
> +
> +static u8 hpt3xx_udma_filter(ide_drive_t *drive)
>  {
>  	struct hpt_info *info	= pci_get_drvdata(HWIF(drive)->pci_dev);
>  	u8 chip_type		= info->chip_type;
> -	u8 mode			= hpt3xx_ratemask(drive);
> -
> -	if (drive->media != ide_disk)
> -		return min(speed, (u8)XFER_PIO_4);
> +	u8 mode			= info->max_mode;
> +	u8 mask;
>  
>  	switch (mode) {
>  		case 0x04:
> -			speed = min_t(u8, speed, XFER_UDMA_6);
> +			mask = 0x7f;
>  			break;
>  		case 0x03:
> -			speed = min_t(u8, speed, XFER_UDMA_5);
> +			mask = 0x3f;
>  			if (chip_type >= HPT374)
>  				break;
>  			if (!check_in_drive_list(drive, bad_ata100_5))
>  				goto check_bad_ata33;
>  			/* fall thru */
>  		case 0x02:
> -			speed = min_t(u8, speed, XFER_UDMA_4);
> +			mask = 0x1f;
>  
>  			/*
>  			 * CHECK ME, Does this need to be changed to HPT374 ??
> @@ -560,13 +548,13 @@ static u8 hpt3xx_ratefilter(ide_drive_t 
>  			    !check_in_drive_list(drive, bad_ata66_4))
>  				goto check_bad_ata33;
>  
> -			speed = min_t(u8, speed, XFER_UDMA_3);
> +			mask = 0x0f;
>  			if (HPT366_ALLOW_ATA66_3 &&
>  			    !check_in_drive_list(drive, bad_ata66_3))
>  				goto check_bad_ata33;
>  			/* fall thru */
>  		case 0x01:
> -			speed = min_t(u8, speed, XFER_UDMA_2);
> +			mask = 0x07;
>  
>  		check_bad_ata33:
>  			if (chip_type >= HPT370A)

   This case 0x01 will *never* be hit for HPT370 chip with the new code, therefore the filter won't get applied.

> @@ -576,10 +564,10 @@ static u8 hpt3xx_ratefilter(ide_drive_t 
>  			/* fall thru */
>  		case 0x00:
>  		default:
> -			speed = min_t(u8, speed, XFER_MW_DMA_2);
> +			mask = 0x00;
>  			break;
>  	}
> -	return speed;
> +	return mask;
>  }
[...]
> @@ -1270,6 +1272,7 @@ static void __devinit init_hwif_hpt366(i
>  	hwif->intrproc			= &hpt3xx_intrproc;
>  	hwif->maskproc			= &hpt3xx_maskproc;
>  	hwif->busproc			= &hpt3xx_busproc;
> +	hwif->udma_filter		= &hpt3xx_udma_filter;

   In fact, we only need a filter for HPT36x/370 chips -- I'll address it in my patch.
 
>  	/*
>  	 * HPT3xxN chips have some complications:

WBR, Sergei