On Sun, Sep 08, 2024 at 05:46:04PM +0800, Huacai Chen wrote: > We use Marvell CD/DVD controllers on many Loongson-based machines. We > found its PIO doesn't work well, and on the opposite its DMA seems work > very well. We don't know the detail of the controller, but we can set > the ATA_FLAG_ATAPI_DMA and ATA_HORKAGE_ATAPI_MOD16_DMA flags on these > controllers to prefer ATAPI DMA. > > BTW, return -EOPNOTSUPP instead of 1 if ATAPI DMA is not supported in > atapi_check_dma(). > > Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx> > --- > drivers/ata/ahci.c | 3 +++ > drivers/ata/libata-core.c | 6 +++++- > include/linux/libata.h | 1 + > 3 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c > index a05c17249448..b195e87e7109 100644 > --- a/drivers/ata/ahci.c > +++ b/drivers/ata/ahci.c > @@ -1939,6 +1939,9 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) > if (hpriv->cap & HOST_CAP_PMP) > pi.flags |= ATA_FLAG_PMP; > > + if (pdev->vendor == PCI_VENDOR_ID_MARVELL_EXT) > + pi.flags |= ATA_FLAG_ATAPI_DMA; > + Hello Huacai, You are not providing a lot of information about: 1) The SATA controller. 2) The CD/DVD drive that you are using. For 1), since you are patching ahci_init_one(), it appears to be a AHCI controller from Marvell. However, we do not write quirks that affect all PCI device IDs for a specific vendor. Please define a new board type in "enum board_ids" in ahci.c, e.g. something like board_ahci_atapi_force_dma or board_ahci_atapi_prefer_dma, and then add specific PCI vendor IDs and device IDs in ahci_pci_tbl that should apply this quirk. For 2), you are not giving us any information, so have you verified that this problem happens with more than one specific CD/DVD drive model? It would be interesting to know if the problem exists even if you are using CD/DVD drives from different vendors. If the problem is only for a specific drive model, then perhaps this shouldn't be a controller quirk, but rather a device quirk? Device specific quirks are defined in __ata_dev_quirks in libata-core.c. Kind regards, Niklas
