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Date: Wed, 9 Nov 2016 10:34:17 +0100
From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To: Nicolas Ferre <nicolas.ferre@...el.com>
Cc: Mark Brown <broonie@...nel.org>, linux@...tdown.ru,
Boris BREZILLON <boris.brezillon@...e-electrons.com>,
linux-spi@...r.kernel.org, geert@...ux-m68k.org,
Ludovic Desroches <ludovic.desroches@...el.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Cyrille Pitchen <cyrille.pitchen@...el.com>,
Wenyou Yang <wenyou.yang@...el.com>
Subject: Re: [PATCH v2] spi: atmel: use managed resource for gpio chip select
On 09/11/2016 at 10:16:18 +0100, Nicolas Ferre wrote :
> Le 08/11/2016 à 18:49, Alexandre Belloni a écrit :
> > On 08/11/2016 at 18:48:52 +0100, Nicolas Ferre wrote :
> >> Use the managed gpio CS pin request so that we avoid having trouble
> >> in the cleanup code.
> >> In fact, if module was configured with DT, cleanup code released
> >> invalid pin. Since resource wasn't freed, module cannot be reinserted.
> >>
> >> This require to extract the gpio request call from the "setup" function
> >> and call it in the appropriate probe function.
> >>
> >> Reported-by: Alexander Morozov <linux@...tdown.ru>
> >> Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
> >
> > I think that's fine but I still have that item on my todo list
> > (discussion in july 2014 with Mark):
> >
> > ---
> >>> Mark: maybe it would make sense to do devm_gpio_request_one() in
> >>> of_spi_register_master(), after of_get_named_gpio.
> >
> >> You need to transition all the drivers doing things manually but yes.
> >> As I keep saying all the GPIO handling needs to be completely
> >> refactored.
> > ---
>
> Would make sense indeed as we are currently doing the same node scanning
> twice...
>
> But this patch actually fixes an issue with module unloading/re-loading
> and freeing of a wrong gpio. So I do think that we shouldn't hold its
> adoption while thinking about this enhancement...
>
Yes, this patch is still useful as-is and fixes a bug.
> Regards,
>
> >> ---
> >> v2: fix devm_gpio_request location: the setup code for device was not proper
> >> location. Move it to the probe function and add needed DT routines to
> >> handle all CS gpio specified.
> >>
> >> drivers/spi/spi-atmel.c | 50 ++++++++++++++++++++++++++++++++++++++-----------
> >> 1 file changed, 39 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> >> index 32683a13dd60..a60925614480 100644
> >> --- a/drivers/spi/spi-atmel.c
> >> +++ b/drivers/spi/spi-atmel.c
> >> @@ -24,6 +24,7 @@
> >>
> >> #include <linux/io.h>
> >> #include <linux/gpio.h>
> >> +#include <linux/of_gpio.h>
> >> #include <linux/pinctrl/consumer.h>
> >> #include <linux/pm_runtime.h>
> >>
> >> @@ -1204,7 +1205,6 @@ static int atmel_spi_setup(struct spi_device *spi)
> >> u32 csr;
> >> unsigned int bits = spi->bits_per_word;
> >> unsigned int npcs_pin;
> >> - int ret;
> >>
> >> as = spi_master_get_devdata(spi->master);
> >>
> >> @@ -1247,16 +1247,9 @@ static int atmel_spi_setup(struct spi_device *spi)
> >> if (!asd)
> >> return -ENOMEM;
> >>
> >> - if (as->use_cs_gpios) {
> >> - ret = gpio_request(npcs_pin, dev_name(&spi->dev));
> >> - if (ret) {
> >> - kfree(asd);
> >> - return ret;
> >> - }
> >> -
> >> + if (as->use_cs_gpios)
> >> gpio_direction_output(npcs_pin,
> >> !(spi->mode & SPI_CS_HIGH));
> >> - }
> >>
> >> asd->npcs_pin = npcs_pin;
> >> spi->controller_state = asd;
> >> @@ -1471,13 +1464,11 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
> >> static void atmel_spi_cleanup(struct spi_device *spi)
> >> {
> >> struct atmel_spi_device *asd = spi->controller_state;
> >> - unsigned gpio = (unsigned long) spi->controller_data;
> >>
> >> if (!asd)
> >> return;
> >>
> >> spi->controller_state = NULL;
> >> - gpio_free(gpio);
> >> kfree(asd);
> >> }
> >>
> >> @@ -1499,6 +1490,39 @@ static void atmel_get_caps(struct atmel_spi *as)
> >> }
> >>
> >> /*-------------------------------------------------------------------------*/
> >> +static int atmel_spi_gpio_cs(struct platform_device *pdev)
> >> +{
> >> + struct spi_master *master = platform_get_drvdata(pdev);
> >> + struct atmel_spi *as = spi_master_get_devdata(master);
> >> + struct device_node *np = master->dev.of_node;
> >> + int i;
> >> + int ret = 0;
> >> + int nb = 0;
> >> +
> >> + if (!as->use_cs_gpios)
> >> + return 0;
> >> +
> >> + if (!np)
> >> + return 0;
> >> +
> >> + nb = of_gpio_named_count(np, "cs-gpios");
> >> + for (i = 0; i < nb; i++) {
> >> + int cs_gpio = of_get_named_gpio(pdev->dev.of_node,
> >> + "cs-gpios", i);
> >> +
> >> + if (cs_gpio == -EPROBE_DEFER)
> >> + return cs_gpio;
> >> +
> >> + if (gpio_is_valid(cs_gpio)) {
> >> + ret = devm_gpio_request(&pdev->dev, cs_gpio,
> >> + dev_name(&pdev->dev));
> >> + if (ret)
> >> + return ret;
> >> + }
> >> + }
> >> +
> >> + return 0;
> >> +}
> >>
> >> static int atmel_spi_probe(struct platform_device *pdev)
> >> {
> >> @@ -1577,6 +1601,10 @@ static int atmel_spi_probe(struct platform_device *pdev)
> >> master->num_chipselect = 4;
> >> }
> >>
> >> + ret = atmel_spi_gpio_cs(pdev);
> >> + if (ret)
> >> + goto out_unmap_regs;
> >> +
> >> as->use_dma = false;
> >> as->use_pdc = false;
> >> if (as->caps.has_dma_support) {
> >> --
> >> 2.9.0
> >>
> >
>
>
> --
> Nicolas Ferre
--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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