From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Jan Kiszka <jan.kiszka@siemens.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 21:07:17 +0200 [thread overview]
Message-ID: <1484593637.2133.152.camel@linux.intel.com> (raw)
In-Reply-To: <7b15a0910a3ad861fd32161c72559bafa7b71e29.1484592296.git.jan.kiszka@siemens.com>
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? Btw, can TINTE
bit be set again during a loop?
> + /* 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.
>
> - 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?) ?
> + sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1);
> + }
> }
>
> /*
--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
next prev parent reply other threads:[~2017-01-16 19:11 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 [this message]
2017-01-16 19:46 ` Jan Kiszka
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
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