From: <Dan.Sneddon@microchip.com>
To: <broonie@kernel.org>, <Dan.Sneddon@microchip.com>
Cc: <linux-spi@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <Tudor.Ambarus@microchip.com>,
<Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
<Ludovic.Desroches@microchip.com>
Subject: Re: Re: [PATCH] spi: atmel: Fix CS and initialization bug
Date: Tue, 29 Jun 2021 17:50:45 +0000 [thread overview]
Message-ID: <cb709000-7816-3817-b734-e03735788723@microchip.com> (raw)
In-Reply-To: <20210629170741.GF4613@sirena.org.uk>
On 6/29/21 10:07 AM, Mark Brown wrote:
> On Tue, Jun 29, 2021 at 05:01:57PM +0000, Dan.Sneddon@microchip.com wrote:
>> On 6/29/21 9:47 AM, Mark Brown wrote:
>
>> >In what way does it do that? I can't tell what the patch is supposed >to
>> >do.
>
>> The SPI_MASTER_GPIO_SS flag has to be set so that the set_cs function
>> gets called even when using gpio cs pins.
>
> This all needs to be clear in the changelog.
I'll update the commit message.
>
>> >> - enable =3D (!!(spi->mode & SPI_CS_HIGH) =3D=3D enable);
>> >> =20
>> >> - if (enable) {
>> >> + if ((enable && (spi->mode & SPI_CS_HIGH))
>> >> + || (!enable && !(spi->mode & SPI_CS_HIGH))) {
>
>> >This looks especially suspicious.
>
>> It's due to the fact that the spi core tells set_cs if the cs should be
>> high or low, not active or disabled. This logic is to convert from
>> high/low to active/disabled.
>
> spi_set_cs() handles SPI_CS_HIGH... this looks like a separate existing
> driver bug, it should just be ignoring SPI_CS_HIGH if it's providing a
> set_cs() operation and letting the core implement SPI_CS_HIGH for it. I
> only checked breifly but it looks like spi-atmel is trying to use the
> core support for chipselect handling here.
>
prev parent reply other threads:[~2021-06-29 17:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-29 16:29 [PATCH] spi: atmel: Fix CS and initialization bug Dan Sneddon
2021-06-29 16:47 ` Mark Brown
2021-06-29 17:01 ` Dan.Sneddon
2021-06-29 17:07 ` Mark Brown
2021-06-29 17:50 ` Dan.Sneddon [this message]
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