linux-kernel - Re: [PATCHv3] w1: omap-hdq: Simplify driver with PM runtime autosuspend

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Date:   Wed, 29 Apr 2020 14:38:17 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Andreas Kemnade <andreas@...nade.info>,
        Evgeniy Polyakov <zbr@...emap.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-omap <linux-omap@...r.kernel.org>,
        Adam Ford <aford173@...il.com>,
        "Andrew F . Davis" <afd@...com>, Vignesh R <vigneshr@...com>
Subject: Re: [PATCHv3] w1: omap-hdq: Simplify driver with PM runtime
 autosuspend

* H. Nikolaus Schaller <hns@...delico.com> [200429 21:35]:
> I have reworked the way the spinlocks, setting and resetting
> of the hdq_irqstatus bits are done and now it works right from
> start of boot. Without any timeouts or delays.
> 
> I am not exactly sure what went wrong, but it seems as if
> the read is already done when the write interrupt status
> bit is processed. Then, the old logic did wipe out both
> bits by hdq_reset_irqstatus() and the read code did timeout
> because it did not notice that the data had already been
> available. This may depend on other system activities so
> that it can explain why other tests didn't reveal it.
> 
> omap_hdq_runtime_resume() and omap_hdq_runtime_suspend()
> also behave fine.
> 
> Before I can post something I need to clean up my hacks
> and add similar fixes to omap_hdq_break() and omap_w1_triplet()
> where I hope that I don't break those...

OK good to hear you were able to figure out what is
going on here.

Regards,

Tony