[PATCH v3 1/1] ata: sata_rescan must scan for block devices

[Tony Dinh]

Hi Simon,

On Fri, Aug 16, 2024 at 3:32 AM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Heinrich,
>
> On Wed, 14 Aug 2024 at 06:53, Heinrich Schuchardt
> <heinrich.schuchardt at canonical.com> wrote:
> >
> > On 14.08.24 14:40, Simon Glass wrote:
> > > On Wed, 14 Aug 2024 at 01:10, Heinrich Schuchardt
> > > <heinrich.schuchardt at canonical.com> wrote:
> > >>
> > >> A system may have multiple SATA controller. Removing the controller with
> > >> the lowest sequence number before probing all SATA controllers makes no
> > >> sense.
> > >>
> > >> In sata_rescan we remove all block devices which are children of SATA
> > >> controllers. We also have to remove the bootdev devices as they will be
> > >> created when scanning for block devices.
> > >>
> > >> After probing all SATA controllers we must scan for block devices otherwise
> > >> we end up without any SATA block device.
> > >>
> > >> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> > >> ---
> > >> v3:
> > >>          continue unbinding and scanning if one device fails
> > >>          write a message if scanning fails
> > >>          add device name to error message
> > >> v2:
> > >>          Scanning for device on an unprobed SATA controller leads
> > >>          to an illegal memory access.
> > >>          Use uclass_foreach_dev_probe() instead of uclass_foreach_dev().
> > >> ---
> > >>   drivers/ata/sata.c | 48 +++++++++++++++++++++++++---------------------
> > >>   1 file changed, 26 insertions(+), 22 deletions(-)
> > >>
> > >> diff --git a/drivers/ata/sata.c b/drivers/ata/sata.c
> > >> index 84437d3d346..89cd516f3d6 100644
> > >> --- a/drivers/ata/sata.c
> > >> +++ b/drivers/ata/sata.c
> > >> @@ -9,9 +9,12 @@
> > >>    *             Dave Liu <daveliu at freescale.com>
> > >>    */
> > >>
> > >> +#define LOG_CATEGORY UCLASS_AHCI
> > >> +
> > >>   #include <ahci.h>
> > >>   #include <blk.h>
> > >>   #include <dm.h>
> > >> +#include <log.h>
> > >>   #include <part.h>
> > >>   #include <sata.h>
> > >>   #include <dm/device-internal.h>
> > >> @@ -49,38 +52,39 @@ int sata_scan(struct udevice *dev)
> > >>
> > >>   int sata_rescan(bool verbose)
> > >>   {
> > >> +       struct uclass *uc;
> > >> +       struct udevice *dev; /* SATA controller */
> > >>          int ret;
> > >> -       struct udevice *dev;
> > >>
> > >>          if (verbose)
> > >> -               printf("Removing devices on SATA bus...\n");
> > >> -
> > >> -       blk_unbind_all(UCLASS_AHCI);
> > >> -
> > >> -       ret = uclass_find_first_device(UCLASS_AHCI, &dev);
> > >> -       if (ret || !dev) {
> > >> -               printf("Cannot find SATA device (err=%d)\n", ret);
> > >> -               return -ENOENT;
> > >> -       }
> > >> -
> > >> -       ret = device_remove(dev, DM_REMOVE_NORMAL);
> > >> -       if (ret) {
> > >> -               printf("Cannot remove SATA device '%s' (err=%d)\n", dev->name, ret);
> > >> -               return -ENOSYS;
> > >> +               printf("scanning bus for devices...\n");
> > >> +
> > >> +       ret = uclass_get(UCLASS_AHCI, &uc);
> > >> +       if (ret)
> > >> +               return ret;
> > >> +
> > >> +       /* Remove all children of SATA devices (blk and bootdev) */
> > >> +       uclass_foreach_dev(dev, uc) {
> > >> +               log_debug("unbind %s\n", dev->name);
> > >> +               ret = device_chld_remove(dev, NULL, DM_REMOVE_NORMAL);
> > >> +               if (!ret)
> > >> +                       ret = device_chld_unbind(dev, NULL);
> > >> +               if (ret && verbose) {
> > >> +                       log_err("Unbinding from %s failed (%dE)\n",
> > >> +                               dev->name, ret);
> > >> +               }
> > >>          }
> > >
> > > This code is in usb_stop() to, so please put it in a shared function.
> > > How about uclass_unbind_children(enum uclass_id) ?
> >
> > git grep -A5 -n uclass_foreach_dev | grep device_chld_remove
> >
> > only finds
> >
> > drivers/scsi/scsi.c-571-
> >                  ret = device_chld_remove(dev, NULL, DM_REMOVE_NORMAL);
> >
> > Where did you see matching USB code?
>
> It is in usb_stop() as I said above. See drivers/usb/host/usb-uclass.c
>
> There might be other similar code, but what SATA is doing here is
> similar to what others do, or want to do.

IMHO, in the current implementation, the abstraction level is just
right for the SATA, SCSI, and USB uclasses. There is no need to
commonize further. I would keep the (re)scanning logic separate for
each type of these devices.

All the best,
Tony

>
> Regards,
> Simon
>
>
> >
> > scsi_scan() could also use a rewrite to avoid stopping at the first error.
> >
> > I guess sata_rescan() and scsi_scan() could be the same function taking
> > a uclass ID as an argument?
> >
> > Best regards
> >
> > Heinrich
> >
> > >
> > >>
> > >>          if (verbose)
> > >>                  printf("Rescanning SATA bus for devices...\n");
> > >>
> > >> -       ret = uclass_probe_all(UCLASS_AHCI);
> > >> -
> > >> -       if (ret == -ENODEV) {
> > >> -               if (verbose)
> > >> -                       printf("No SATA block device found\n");
> > >> -               return 0;
> > >> +       uclass_foreach_dev_probe(UCLASS_AHCI, dev) {
> > >> +               ret = sata_scan(dev);
> > >> +               if (ret && verbose)
> > >> +                       log_err("Scanning %s failed (%dE)\n", dev->name, ret);
> > >>          }
> > >>
> > >> -       return ret;
> > >> +       return 0;
> > >>   }
> > >>
> > >>   static unsigned long sata_bread(struct udevice *dev, lbaint_t start,
> > >> --
> > >> 2.45.2
> > >>
> > >
> > > If you have time, please add a test for ahci (dm/test/ahci)
> > >
> > > Regards,
> > > Simon
> >