linux-kernel - Re: [RFC 03/11] hte: Add tegra194 HTE kernel provider

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Date:   Sat, 7 Aug 2021 12:51:16 +0800
From:   Kent Gibson <warthog618@...il.com>
To:     Dipen Patel <dipenp@...dia.com>
Cc:     thierry.reding@...il.com, jonathanh@...dia.com,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-gpio@...r.kernel.org, linus.walleij@...aro.org,
        bgolaszewski@...libre.com, devicetree@...r.kernel.org,
        linux-doc@...r.kernel.org, robh+dt@...nel.org
Subject: Re: [RFC 03/11] hte: Add tegra194 HTE kernel provider

On Fri, Aug 06, 2021 at 09:52:54PM -0700, Dipen Patel wrote:
> 
> On 8/6/21 8:07 PM, Kent Gibson wrote:
> > On Fri, Aug 06, 2021 at 07:41:09PM -0700, Dipen Patel wrote:
> >> On 7/31/21 8:43 AM, Kent Gibson wrote:
> >>> On Wed, Jul 28, 2021 at 04:59:08PM -0700, Dipen Patel wrote:
> >>>> Thanks Kent for the review comment. My responses inline.
> >>>>

<snip>

> >
> >> 2. Does hte handler solution create race between two handlers? i.e. edge_irq_handler and
> >>
> >> hte_handler, for the worst case scenario as below?
> >>
> > No.  If hardware timestamp is selected then no irq is requested from the
> > irq subsystem for that line - only from the hte subsystem instead.
> > So there will be no edge_irq_handler call for that line, so no possible race.
> 
> That is not possible for certain providers, for example the one I am dealing
> 
> with which requires GPIO line to be requested as input and IRQ needs to
> 
> be enabled on them.
> 

So, for your hte subsystem to work, the consumer has to also request
a line from the irq subsystem?  That makes sense to you?
Have hte do that, rather than the consumer.

And another reason it makes sense to integrate this with irq...

Cheers,
Kent.