Messages in this thread | | | Date | Mon, 11 Oct 2021 15:35:56 +0200 | From | Sean Nyekjaer <> | Subject | Re: [PATCH 3/3] mtd: mtdconcat: add suspend lock handling |
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On Mon, Oct 11, 2021 at 03:27:03PM +0200, Boris Brezillon wrote: > On Mon, 11 Oct 2021 15:15:01 +0200 > Boris Brezillon <boris.brezillon@collabora.com> wrote: > > > On Mon, 11 Oct 2021 13:52:53 +0200 > > Sean Nyekjaer <sean@geanix.com> wrote: > > > > > Use new suspend lock handling for this special case for concatenated > > > MTD devices. > > > > > > Fixes: 013e6292aaf5 ("mtd: rawnand: Simplify the locking") > > > Signed-off-by: Sean Nyekjaer <sean@geanix.com> > > > --- > > > drivers/mtd/mtdconcat.c | 11 +++++++++-- > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c > > > index f685a581df48..c497c851481f 100644 > > > --- a/drivers/mtd/mtdconcat.c > > > +++ b/drivers/mtd/mtdconcat.c > > > @@ -561,25 +561,32 @@ static void concat_sync(struct mtd_info *mtd) > > > > > > static int concat_suspend(struct mtd_info *mtd) > > > { > > > + struct mtd_info *master = mtd_get_master(mtd); > > > struct mtd_concat *concat = CONCAT(mtd); > > > int i, rc = 0; > > > > > > for (i = 0; i < concat->num_subdev; i++) { > > > struct mtd_info *subdev = concat->subdev[i]; > > > - if ((rc = mtd_suspend(subdev)) < 0) > > > + > > > + down_write(&master->master.suspend_lock); > > > + if ((rc = __mtd_suspend(subdev)) < 0) > > > return rc; > > > + up_write(&master->master.suspend_lock); > > > } > > > return rc; > > > } > > > > > > static void concat_resume(struct mtd_info *mtd) > > > { > > > + struct mtd_info *master = mtd_get_master(mtd); > > > struct mtd_concat *concat = CONCAT(mtd); > > > int i; > > > > > > for (i = 0; i < concat->num_subdev; i++) { > > > struct mtd_info *subdev = concat->subdev[i]; > > > - mtd_resume(subdev); > > > + down_write(&master->master.suspend_lock); > > > + __mtd_resume(subdev); > > > + up_write(&master->master.suspend_lock); > > > } > > > } > > > > > > > Why do we need to implement the _suspend/_resume() hooks here? The > > underlying MTD devices should be suspended at some point (when the > > class ->suspend() method is called on those device), and there's > > nothing mtdconcat-specific to do here. Looks like implementing this > > suspend-all-subdevs loop results in calling mtd->_suspend()/_resume() > > twice, which is useless. The only issue I see is if the subdevices > > haven't been registered to the device model, but that happens, I > > believe we have bigger issues (those devices won't be suspended when > > mtdconcat is not used). > > > Uh, just had a look at mtd_concat_create() callers, and they indeed > don't register the subdevices, so I guess the suspend-all-subdevs loop > is needed. I really thought mtdconcat was something more generic > aggregating already registered devices...
Hi Boris,
Cool, mtd_concat should be seen as mtd devices concatenated? Could be spi-nors and rawnand. So _suspend() needs to be called for every device layer?
From what I see here, mtd_suspend()/mtd_resume() is called for every mtd device. Before this patch mtd_suspend() would only have effect on the first device as master->master.suspended is set and then calls to device specific _suspend() is skipped.
Correct?
/Sean
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