It's merely a moving of comment moving for/and a no-behavioral-change adaptation for the reversion. Similar has been done in the equivalent patch for the UAS driver (and the reason is stated there). On Mon, 30 Nov 2020 at 17:50, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > Hi, > > On 11/28/20 4:48 PM, Tom Yan wrote: > > While the change only seemed to have caused issue on uas drives, we > > probably want to avoid it in the usb-storage driver as well, until > > we are sure it is the right thing to do. > > > > Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx> > > This seems to do a whole lot more then just dropping back from > scsi_add_host_with_dma() to scsi_add_host(). This has way more > lines then the orginal commit. > > IMHO it would be best to just revert commit 0154012f8018bba4d9971d1007c12ffd48539ddb > and then submit these changes as a separate patch (which would be > 5.11 material then). > > That separate patch could then also have a proper commit message > explaining the other changes you are making, which is also not > unimportant. > > Regards, > > Hans > > > > > > --- > > drivers/usb/storage/scsiglue.c | 40 +++++++++++++++++----------------- > > drivers/usb/storage/usb.c | 3 +-- > > 2 files changed, 21 insertions(+), 22 deletions(-) > > > > diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c > > index 560efd1479ba..6539bae1c188 100644 > > --- a/drivers/usb/storage/scsiglue.c > > +++ b/drivers/usb/storage/scsiglue.c > > @@ -92,7 +92,7 @@ static int slave_alloc (struct scsi_device *sdev) > > static int slave_configure(struct scsi_device *sdev) > > { > > struct us_data *us = host_to_us(sdev->host); > > - struct device *dev = sdev->host->dma_dev; > > + struct device *dev = us->pusb_dev->bus->sysdev; > > > > /* > > * Many devices have trouble transferring more than 32KB at a time, > > @@ -120,6 +120,25 @@ static int slave_configure(struct scsi_device *sdev) > > * better throughput on most devices. > > */ > > blk_queue_max_hw_sectors(sdev->request_queue, 2048); > > + } else { > > + /* > > + * Limit the total size of a transfer to 120 KB. > > + * > > + * Some devices are known to choke with anything larger. It seems like > > + * the problem stems from the fact that original IDE controllers had > > + * only an 8-bit register to hold the number of sectors in one transfer > > + * and even those couldn't handle a full 256 sectors. > > + * > > + * Because we want to make sure we interoperate with as many devices as > > + * possible, we will maintain a 240 sector transfer size limit for USB > > + * Mass Storage devices. > > + * > > + * Tests show that other operating have similar limits with Microsoft > > + * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3 > > + * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2 > > + * and 2048 for USB3 devices. > > + */ > > + blk_queue_max_hw_sectors(sdev->request_queue, 240); > > } > > > > /* > > @@ -627,25 +646,6 @@ static const struct scsi_host_template usb_stor_host_template = { > > .sg_tablesize = SG_MAX_SEGMENTS, > > > > > > - /* > > - * Limit the total size of a transfer to 120 KB. > > - * > > - * Some devices are known to choke with anything larger. It seems like > > - * the problem stems from the fact that original IDE controllers had > > - * only an 8-bit register to hold the number of sectors in one transfer > > - * and even those couldn't handle a full 256 sectors. > > - * > > - * Because we want to make sure we interoperate with as many devices as > > - * possible, we will maintain a 240 sector transfer size limit for USB > > - * Mass Storage devices. > > - * > > - * Tests show that other operating have similar limits with Microsoft > > - * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3 > > - * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2 > > - * and 2048 for USB3 devices. > > - */ > > - .max_sectors = 240, > > - > > /* emulated HBA */ > > .emulated = 1, > > > > diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c > > index c2ef367cf257..f177da4ff1bc 100644 > > --- a/drivers/usb/storage/usb.c > > +++ b/drivers/usb/storage/usb.c > > @@ -1050,8 +1050,7 @@ int usb_stor_probe2(struct us_data *us) > > usb_autopm_get_interface_no_resume(us->pusb_intf); > > snprintf(us->scsi_name, sizeof(us->scsi_name), "usb-storage %s", > > dev_name(dev)); > > - result = scsi_add_host_with_dma(us_to_host(us), dev, > > - us->pusb_dev->bus->sysdev); > > + result = scsi_add_host(us_to_host(us), dev); > > if (result) { > > dev_warn(dev, > > "Unable to add the scsi host\n"); > > >