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

Bartlomiej Zolnierkiewicz wrote:

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

Here's another portion of comments...

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

> * add ide_hwif_t.filter_udma_mask hook for filtering UDMA mask

Erm, maybe a shorter method name like udma_filter would go with the others
better. But well, that's my taste. :-)

> (use it in alim15x3, hpt366, siimage and serverworks drivers)
> * add ide_max_dma_mode() for finding best DMA mode for the device
> (loosely based on some older libata-core.c code)
> * convert ide_dma_speed() users to use ide_max_dma_mode()
> * make ide_rate_filter() take "ide_drive_t *drive" as an argument instead
> of "u8 mode" and teach it to how to use UDMA mask to do filtering
> * use ide_rate_filter() in hpt366 driver
> * remove no longer needed ide_dma_speed() and *_ratemask()
> * unexport eighty_ninty_three()

> 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->filter_udma_mask)
> + mask &= hwif->filter_udma_mask(drive);
> +
> + if ((mask & 0x78) && (eighty_ninty_three(drive) == 0))
> + mask &= 0x07;
> + 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);
> +

I didn't quite like the array/loop approach but well, that's my taste (I'd
rather put the mode-from-mask evaluation to the function and call it thrice)...

> Index: b/drivers/ide/ide-lib.c
> ===================================================================
> --- a/drivers/ide/ide-lib.c
> +++ b/drivers/ide/ide-lib.c
> @@ -69,123 +69,34 @@ char *ide_xfer_verbose (u8 xfer_rate)
> EXPORT_SYMBOL(ide_xfer_verbose);
>
> /**
> - * ide_dma_speed - compute DMA speed
> - * @drive: drive
> - * @mode: modes available
> - *
> - * 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_dma_speed(ide_drive_t *drive, u8 mode)

[...]

> -EXPORT_SYMBOL(ide_dma_speed);

Alas, my ide_dma_speed() fix is going to be oudated rather quickly... :-)

> 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_filter_udma_mask(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)
> @@ -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;
> }

Erm, I see. This driver will need some redesign because 'struct hpt_info'
was fitted for the old rate filtering model. Looks like the 'max_mode' field
should be replaced by 'ultra_mask' there...

> static u32 get_speed_setting(u8 speed, struct hpt_info *info)
> @@ -607,12 +595,19 @@ static int hpt36x_tune_chipset(ide_drive
> ide_hwif_t *hwif = HWIF(drive);
> struct pci_dev *dev = hwif->pci_dev;
> struct hpt_info *info = pci_get_drvdata(dev);
> - u8 speed = hpt3xx_ratefilter(drive, xferspeed);
> + u8 speed = ide_rate_filter(drive, xferspeed);
> u8 itr_addr = drive->dn ? 0x44 : 0x40;
> - u32 itr_mask = speed < XFER_MW_DMA_0 ? 0x30070000 :
> - (speed < XFER_UDMA_0 ? 0xc0070000 : 0xc03800ff);
> - u32 new_itr = get_speed_setting(speed, info);
> u32 old_itr = 0;
> + u32 itr_mask, new_itr;
> +
> + /* TODO: move this to ide_rate_filter() [ check ->atapi_dma ] */
> + if (drive->media != ide_disk)
> + speed = min_t(u8, speed, XFER_PIO_4);
> +

When I think about it, it seems quite stupid to set a PIO mode instead of
a requested DMA one. So, this is actually a questionable piece of code in
this driver...

Well, I must note the sorrow fact that both the IDE susbsytem as a whole
doesn't keep track of PIO/DMA modes separately (having only current_mode) and
the many drivers also fail to handle the timing registers shared by PIO/DMA
modes correctly (well, it's actually also a hardware design issue :-).

> + itr_mask = speed < XFER_MW_DMA_0 ? 0x30070000 :
> + (speed < XFER_UDMA_0 ? 0xc0070000 : 0xc03800ff);
> +
> + new_itr = get_speed_setting(speed, info);

Well, I liked this code where it was. But anyway, it's going to be
replaced RSN...

> @@ -632,12 +627,19 @@ static int hpt37x_tune_chipset(ide_drive
> ide_hwif_t *hwif = HWIF(drive);
> struct pci_dev *dev = hwif->pci_dev;
> struct hpt_info *info = pci_get_drvdata(dev);
> - u8 speed = hpt3xx_ratefilter(drive, xferspeed);
> + u8 speed = ide_rate_filter(drive, xferspeed);
> u8 itr_addr = 0x40 + (drive->dn * 4);
> - u32 itr_mask = speed < XFER_MW_DMA_0 ? 0x303c0000 :
> - (speed < XFER_UDMA_0 ? 0xc03c0000 : 0xc1c001ff);
> - u32 new_itr = get_speed_setting(speed, info);
> u32 old_itr = 0;
> + u32 itr_mask, new_itr;
> +
> + /* TODO: move this to ide_rate_filter() [ check ->atapi_dma ] */
> + if (drive->media != ide_disk)
> + speed = min_t(u8, speed, XFER_PIO_4);
> +
> + itr_mask = speed < XFER_MW_DMA_0 ? 0x303c0000 :
> + (speed < XFER_UDMA_0 ? 0xc03c0000 : 0xc1c001ff);
> +
> + new_itr = get_speed_setting(speed, info);

Same comments here...

> Index: b/drivers/ide/pci/serverworks.c
> ===================================================================
> --- a/drivers/ide/pci/serverworks.c
> +++ b/drivers/ide/pci/serverworks.c
> @@ -65,16 +65,16 @@ static int check_in_drive_lists (ide_dri
> return 0;
> }
>
> -static u8 svwks_ratemask (ide_drive_t *drive)
> +static u8 svwks_filter_udma_mask(ide_drive_t *drive)
> {
> struct pci_dev *dev = HWIF(drive)->pci_dev;
> - u8 mode = 0;
> + u8 mask = 0;

Hm, this looks like it needs rework...

> if (!svwks_revision)
> pci_read_config_byte(dev, PCI_REVISION_ID, &svwks_revision);
>
> if (dev->device == PCI_DEVICE_ID_SERVERWORKS_HT1000IDE)
> - return 2;
> + return 0x1f;
> if (dev->device == PCI_DEVICE_ID_SERVERWORKS_OSB4IDE) {
> u32 reg = 0;
> if (isa_dev)
> @@ -86,25 +86,31 @@ static u8 svwks_ratemask (ide_drive_t *d
> if(drive->media == ide_disk)
> return 0;
> /* Check the OSB4 DMA33 enable bit */
> - return ((reg & 0x00004000) == 0x00004000) ? 1 : 0;
> + return ((reg & 0x00004000) == 0x00004000) ? 0x07 : 0;
> } else if (svwks_revision < SVWKS_CSB5_REVISION_NEW) {
> - return 1;
> + return 0x07;
> } else if (svwks_revision >= SVWKS_CSB5_REVISION_NEW) {
> - u8 btr = 0;
> + u8 btr = 0, mode;
> pci_read_config_byte(dev, 0x5A, &btr);
> mode = btr & 0x3;
> - if (!eighty_ninty_three(drive))
> - mode = min(mode, (u8)1);
> +
> /* If someone decides to do UDMA133 on CSB5 the same
> issue will bite so be inclusive */
> if (mode > 2 && check_in_drive_lists(drive, svwks_bad_ata100))
> mode = 2;
> +
> + switch(mode) {
> + case 2: mask = 0x1f; break;
> + case 1: mask = 0x07; break;
> + default: mask = 0x00; break;
> + }
> }
> if (((dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB6IDE) ||
> (dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB6IDE2)) &&
> (!(PCI_FUNC(dev->devfn) & 1)))
> - mode = 2;
> - return mode;
> + mask = 0x1f;
> +
> + return mask;
> }

Hm, what was the problem with setting the proper masks based on PCI device
ID in the init. code?
That'd have greatly simplified the filter...

> Index: b/drivers/ide/pci/siimage.c
> ===================================================================
> --- a/drivers/ide/pci/siimage.c
> +++ b/drivers/ide/pci/siimage.c
> @@ -116,45 +116,41 @@ static inline unsigned long siimage_seld
> }
>
> /**
> - * siimage_ratemask - Compute available modes
> - * @drive: IDE drive
> + * sil_filter_udma_mask - compute UDMA mask
> + * @drive: IDE device
> + *
> + * Compute the available UDMA speeds for the device on the interface.
> *
> - * Compute the available speeds for the devices on the interface.
> * For the CMD680 this depends on the clocking mode (scsc), for the
> - * SI3312 SATA controller life is a bit simpler. Enforce UDMA33
> - * as a limit if there is no 80pin cable present.
> + * SI3112 SATA controller life is a bit simpler.
> */
> -
> -static byte siimage_ratemask (ide_drive_t *drive)
> +
> +static u8 sil_filter_udma_mask(ide_drive_t *drive)
> {
> - ide_hwif_t *hwif = HWIF(drive);
> - u8 mode = 0, scsc = 0;
> + ide_hwif_t *hwif = drive->hwif;
> unsigned long base = (unsigned long) hwif->hwif_data;
> + u8 mask = 0, scsc = 0;
>
> if (hwif->mmio)
> scsc = hwif->INB(base + 0x4A);
> else
> pci_read_config_byte(hwif->pci_dev, 0x8A, &scsc);
>
> - if(is_sata(hwif))
> - {
> - if(strstr(drive->id->model, "Maxtor"))
> - return 3;
> - return 4;
> + if (is_sata(hwif)) {
> + mask = strstr(drive->id->model, "Maxtor") ? 0x3f : 0x7f;
> + goto out;
> }
> -
> +
> if ((scsc & 0x30) == 0x10) /* 133 */
> - mode = 4;
> + mask = 0x7f;
> else if ((scsc & 0x30) == 0x20) /* 2xPCI */
> - mode = 4;
> + mask = 0x7f;
> else if ((scsc & 0x30) == 0x00) /* 100 */
> - mode = 3;
> + mask = 0x3f;
> else /* Disabled ? */
> BUG();

Most probably this is doable at init. time also...

MBR, Sergei

PS: I understand that the intent wasn not to make this rewrite optimal but
do it quick and with least affect. And I certainly may handle hpt366.c
redesign... :-)

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