From: Jan Kiszka <jan.kiszka@siemens.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Mark Brown <broonie@kernel.org>
Cc: linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
Daniel Mack <daniel@zonque.org>,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Robert Jarzmik <robert.jarzmik@free.fr>,
linux-kernel@vger.kernel.org,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>
Subject: Re: [PATCH v2 2/3] spi: pxa2xx: Prepare for edge-triggered interrupts
Date: Mon, 16 Jan 2017 20:46:05 +0100 [thread overview]
Message-ID: <7fd7a8eb-4302-523b-08dd-f2a28b845a5e@siemens.com> (raw)
In-Reply-To: <1484593637.2133.152.camel@linux.intel.com>
On 2017-01-16 20:07, Andy Shevchenko wrote:
> On Mon, 2017-01-16 at 19:44 +0100, Jan Kiszka wrote:
>> When using the a device with edge-triggered interrupts, such as MSIs,
>> the interrupt handler has to ensure that there is a point in time
>> during
>> its execution where all interrupts sources are silent so that a new
>> event can trigger a new interrupt again.
>>
>> This is achieved here by looping over SSSR evaluation. We need to take
>> into account that SSCR1 may be changed by the transfer handler, thus
>> we
>> need to redo the mask calculation, at least regarding the volatile
>> interrupt enable bit (TIE).
>>
>
> So, more comments/questions below.
>
>>
>> sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1);
>>
>> - /* Ignore possible writes if we don't need to write */
>> - if (!(sccr1_reg & SSCR1_TIE))
>> - mask &= ~SSSR_TFS;
>> -
>> /* Ignore RX timeout interrupt if it is disabled */
>> if (!(sccr1_reg & SSCR1_TINTE))
>> mask &= ~SSSR_TINT;
>>
>> - if (!(status & mask))
>> - return IRQ_NONE;
>> + while (1) {
>
> Can we switch to do-while and move previous block here?
Don't see how this would help (without duplicating more code).
> Btw, can TINTE
> bit be set again during a loop?
Nope, it's statically set, at least so far.
What we could do is simply restarting ssp_int
>
>> + /* Ignore possible writes if we don't need to write
>> */
>> + if (!(sccr1_reg & SSCR1_TIE))
>> + mask &= ~SSSR_TFS;
>>
>> - if (!drv_data->master->cur_msg) {
>> - handle_bad_msg(drv_data);
>> - /* Never fail */
>> - return IRQ_HANDLED;
>> - }
>> + if (!(status & mask))
>> + return ret;
>> +
>> + if (!drv_data->master->cur_msg) {
>> + handle_bad_msg(drv_data);
>> + /* Never fail */
>> + return IRQ_HANDLED;
>> + }
>> +
>
>> + ret |= drv_data->transfer_handler(drv_data);
>
> So, we might call handler several times. This needs to be commented in
> the code why you do so.
I can move the commit log into the code.
>
>>
>> - return drv_data->transfer_handler(drv_data);
>> + status = pxa2xx_spi_read(drv_data, SSSR);
>
> Would it be possible to get all 1:s from the register
> (something/autosuspend just powered off it by timeout?) ?
>
Not sure if that can happen, but I guess it would be simpler and more
readable to simply do this instead:
while (1) {
/*
* If the device is not yet in RPM suspended state and we get an
* interrupt that is meant for another device, check if status
* bits are all set to one. That means that the device is
* already powered off.
*/
status = pxa2xx_spi_read(drv_data, SSSR);
if (status == ~0)
return ret;
sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1);
/* Ignore RX timeout interrupt if it is disabled */
if (!(sccr1_reg & SSCR1_TINTE))
mask &= ~SSSR_TINT;
/* Ignore possible writes if we don't need to write */
if (!(sccr1_reg & SSCR1_TIE))
mask &= ~SSSR_TFS;
if (!(status & mask))
return ret;
if (!drv_data->master->cur_msg) {
handle_bad_msg(drv_data);
/* Never fail */
return IRQ_HANDLED;
}
ret |= drv_data->transfer_handler(drv_data);
}
i.e. preserve the current structure, just add the loop.
Jan
--
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2017-01-16 19:46 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 18:44 [PATCH v2 0/3] spi: pca2xx: Prepare for and enable MSI support Jan Kiszka
2017-01-16 18:44 ` [PATCH v2 1/3] spi: pxa2xx: Factor out handle_bad_msg Jan Kiszka
2017-01-17 11:18 ` Jarkko Nikula
2017-01-17 18:46 ` Applied "spi: pxa2xx: Factor out handle_bad_msg" to the spi tree Mark Brown
2017-01-16 18:44 ` [PATCH v2 2/3] spi: pxa2xx: Prepare for edge-triggered interrupts Jan Kiszka
2017-01-16 19:07 ` Andy Shevchenko
2017-01-16 19:46 ` Jan Kiszka [this message]
2017-01-17 18:52 ` Jan Kiszka
2017-01-17 7:54 ` Robert Jarzmik
2017-01-17 8:05 ` Jan Kiszka
2017-01-18 8:21 ` Robert Jarzmik
2017-01-18 9:33 ` Jan Kiszka
2017-01-18 12:46 ` Mark Brown
2017-01-19 15:34 ` Jan Kiszka
2017-01-19 19:37 ` [PATCH v3 " Jan Kiszka
2017-01-19 19:57 ` Mark Brown
2017-01-19 20:04 ` Andy Shevchenko
2017-01-20 12:21 ` Mark Brown
2017-01-20 15:29 ` Jan Kiszka
2017-01-20 16:14 ` Mark Brown
2017-01-20 7:42 ` Robert Jarzmik
2017-01-24 18:39 ` Applied "spi: pxa2xx: Prepare for edge-triggered interrupts" to the spi tree Mark Brown
2017-01-17 7:58 ` [PATCH v2 2/3] spi: pxa2xx: Prepare for edge-triggered interrupts Robert Jarzmik
2017-01-17 8:10 ` Jan Kiszka
2017-01-17 13:11 ` Jarkko Nikula
2017-01-17 14:43 ` Jan Kiszka
2017-01-16 18:44 ` [PATCH v2 3/3] spi: pca2xx-pci: Allow MSI Jan Kiszka
2017-01-16 19:08 ` Andy Shevchenko
2017-01-17 11:18 ` Jarkko Nikula
2017-01-24 18:39 ` Applied "spi: pca2xx-pci: Allow MSI" to the spi tree Mark Brown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7fd7a8eb-4302-523b-08dd-f2a28b845a5e@siemens.com \
--to=jan.kiszka@siemens.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=broonie@kernel.org \
--cc=daniel@zonque.org \
--cc=haojian.zhuang@gmail.com \
--cc=jarkko.nikula@linux.intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=mika.westerberg@linux.intel.com \
--cc=robert.jarzmik@free.fr \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).