Messages in this thread | | | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: [RFC][PATCH] 2.4 IDE Serverworks OSB4 DMA patch | Date | Thu, 29 Apr 2004 21:32:26 +0200 |
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On Thursday 29 of April 2004 21:04, Patrick Wildi wrote: > I have been using a OSB4 chipset based system with a CompactFlash > that supports PIO only and a laptop IBM/Hitachi Travelstar HDD > that supports UDMA. > For both drives, the serverworks code misconfigures the drives: > > - for the CF (hooked up as /dev/hda), svwks_config_drive_xfer_rate() > will not match any tests (drive->autodma = 0, id->capability = 2, > id->field_valid = 1), but the function will then call > hwif->ide_dma_on(drive), which it should not do for this drive. > This patch moves the enabling of DMA up into the DMA section of > the code.
Yep, known bug, it is fixed in 2.6.
It is present in many other drivers, my 2.6 patch needs to be backported.
> - for the Travelstart HDD, the settings coming into > svwks_config_drive_xfer_rate() are: drive->autodma = 32, > id->capability = 15, id->field_valid = 7, id->dma_ultra = 0x43f. > But as this is an OSB4, the hwif->ultra_mask is set to not support > UDMA. Unfortunately in that case svwks_config_drive_xfer_rate() > falls through to the end of the function, instead of trying > other DMA modes.
Good catch.
It seems the same bug can be present in other drivers too (hint, hint). ;)
> By adding a jump to try_dma_modes in the case that the drive > is UDMA capable but the mask does not allow UDMA, the drive > will be setup up for MWDMA. > > The logic in svwks_config_drive_xfer_rate() could probably be > improved a bit, but I kept the changes to an absolute minium > to reduce the risk of breakage.
OK, thanks.
> The patch is against 2.4.24, but the file has not changed in > 2.4.25 and 2.4.26. > > Patrick > > > --- linux-2.4.24-nam/drivers/ide/pci/serverworks.c.orig Thu Apr 22 17:31:28 > 2004 +++ linux-2.4.24-nam/drivers/ide/pci/serverworks.c Thu Apr 29 11:02:05 > 2004 @@ -473,7 +473,9 @@ > int dma = config_chipset_for_dma(drive); > if ((id->field_valid & 2) && !dma) > goto try_dma_modes; > - } > + } else > + /* UDMA disabled by mask, try other DMA modes */ > + goto try_dma_modes; > } else if (id->field_valid & 2) { > try_dma_modes: > if ((id->dma_mword & hwif->mwdma_mask) || > @@ -490,6 +492,7 @@ > } else { > goto no_dma_set; > } > + return hwif->ide_dma_on(drive); > } else if ((id->capability & 8) || (id->field_valid & 2)) { > fast_ata_pio: > no_dma_set: > @@ -497,7 +500,7 @@ > // hwif->tuneproc(drive, 5); > return hwif->ide_dma_off_quietly(drive); > } > - return hwif->ide_dma_on(drive); > + return 0; > } > > /* This can go soon */
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