From: Fabio Estevam <festevam@gmail.com>
To: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Cc: Mark Brown <broonie@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
NXP Linux Team <linux-imx@nxp.com>,
linux-spi <linux-spi@vger.kernel.org>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] spi-imx: remove num-cs support, set num_chipselect to 4
Date: Fri, 4 Sep 2020 09:35:38 -0300 [thread overview]
Message-ID: <CAOMZO5DGHoG_8X+fbrGCHR4g=sGdEaF7bYrHbC_2T=aUnfTs8g@mail.gmail.com> (raw)
In-Reply-To: <20200903144028.20416-1-matthias.schiffer@ew.tq-group.com>
Hi Matthias,
On Thu, Sep 3, 2020 at 11:40 AM Matthias Schiffer
<matthias.schiffer@ew.tq-group.com> wrote:
>
> The num-cs property is not considered useful, and no in-tree Device
> Trees define it for spi-imx.
>
> The default value to be used when no cs-gpios are defined is set to 4 to
> give access to all native CS pins of modern i.MX SoCs (i.MX6 and newer).
>
> In older SoCs, the number of CS pins varies (for example the i.MX27 has 3
> CS pins on CSPI1 and CSPI2, and only a single CS on CSPI3). Attempting
> to use the nonexisting CS pin would be an easy to notice DT
> misconfiguration; making the driver catch this doesn't seem worthwhile.
>
> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> ---
> drivers/spi/spi-imx.c | 13 +------------
> 1 file changed, 1 insertion(+), 12 deletions(-)
>
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 197f60632072..aece8482739b 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -1581,7 +1581,6 @@ static int spi_imx_probe(struct platform_device *pdev)
> const struct spi_imx_devtype_data *devtype_data = of_id ? of_id->data :
> (struct spi_imx_devtype_data *)pdev->id_entry->driver_data;
> bool slave_mode;
> - u32 val;
>
> slave_mode = devtype_data->has_slavemode &&
> of_property_read_bool(np, "spi-slave");
> @@ -1605,6 +1604,7 @@ static int spi_imx_probe(struct platform_device *pdev)
> master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
> master->bus_num = np ? -1 : pdev->id;
> master->use_gpio_descriptors = true;
> + master->num_chipselect = 4;
On an imx6q-sabresd, which only has one SPI chip-select via GPIO, this
makes the SPI core to understand that it has 4 chip selects.
From spi_get_gpio_descs() in drivers/spi/spi.c:
ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
It is 4 now after your patch, it was 3 after 8cdcd8aeee28 ("spi:
imx/fsl-lpspi: Convert to GPIO descriptors") and 1 before such commit.
Couldn't we just remove master->num_chipselect from the spi-imx.c driver?
next prev parent reply other threads:[~2020-09-04 12:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 14:40 [PATCH] spi-imx: remove num-cs support, set num_chipselect to 4 Matthias Schiffer
2020-09-04 12:35 ` Fabio Estevam [this message]
2020-09-04 13:02 ` (EXT) " Matthias Schiffer
2020-09-04 13:57 ` Fabio Estevam
2020-09-04 14:34 ` (EXT) " Matthias Schiffer
2020-09-04 15:04 ` Mark Brown
2020-09-04 15:42 ` Fabio Estevam
2020-09-07 7:40 ` (EXT) " Matthias Schiffer
2020-09-13 14:15 ` Fabio Estevam
2020-09-04 13:10 ` Mark Brown
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