lkml.org 
[lkml]   [2019]   [Oct]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v9 4/7] nfc: pn533: Split pn533 init & nfc_register
On Tue, Oct 15, 2019 at 09:16:42AM -0700, Jakub Kicinski wrote:
> On Tue, 15 Oct 2019 11:51:24 +0200, Lars Poeschel wrote:
> > > > - priv->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols,
> > > > - priv->ops->tx_header_len +
> > > > - PN533_CMD_DATAEXCH_HEAD_LEN,
> > > > - priv->ops->tx_tail_len);
> > > > - if (!priv->nfc_dev) {
> > > > - rc = -ENOMEM;
> > > > - goto destroy_wq;
> > > > - }
> > > > -
> > > > - nfc_set_parent_dev(priv->nfc_dev, parent);
> > > > - nfc_set_drvdata(priv->nfc_dev, priv);
> > > > -
> > > > - rc = nfc_register_device(priv->nfc_dev);
> > > > - if (rc)
> > > > - goto free_nfc_dev;
> > >
> > > Aren't you moving too much out of here? Looking at commit 32ecc75ded72
> > > ("NFC: pn533: change order operations in dev registation") it seems like
> > > IRQ handler may want to access the data structures, do this change not
> > > reintroduce the problem?
> >
> > Yes, you are right, there could be a problem if an irq gets served
> > before the driver is registered to the nfc subsystem.
> > Well, but the purpose of this patch is exactly that: Prevent use of nfc
> > subsystem before the chip is fully initialized.
> > To address this, I would not change the part above, but move the
> > request_threaded_irq to the very bottom in pn533_i2c_probe, after the
> > call to pn53x_register_nfc. So it is not possible to use nfc before the
> > chip is initialized and irqs don't get served before the driver is
> > registered to nfc subsystem.
> > Thank you for this!
> > I will include this in v10 of the patchset.
>
> You can run nfc_allocate_device() etc. early, then allocate the IRQ,
> and then run nfc_register_device(), would that work? Is that what you
> have in mind?

Well, I think my proposed solution above would technically do it, but I
think I will do it like you proposed. I think for someone reading the
code it is far more easier to understand, what the idea behind it is, if
the irq is requested right between nfc_allocate_device and
nfc_register_device.
Thanks again!

\
 
 \ /
  Last update: 2019-10-16 10:43    [W:0.139 / U:0.812 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site