Revert "spi: gpio: Don't request CS GPIO in DT use-case"

Message ID 20190701172517.31641-1-linus.walleij@linaro.org
State New
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Series
  • Revert "spi: gpio: Don't request CS GPIO in DT use-case"
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Commit Message

Linus Walleij July 1, 2019, 5:25 p.m.
This reverts commit 249e2632dcd0509b8f8f296f5aabf4d48dfd6da8.

After this commit drivers/net/dsa/vitesse-vsc73xx.c stopped
working. Apparently CS is not working because the reads
from the device is just returning just 1:s or just 0:s at
all bisection points, so it is a complete regression and
I think spi-gpio CS is essentially broken.

The revert had to be hand-crafted to preserve all the other
cleanup and changes to this driver, but now it works.

I'm sad to revert the change because it is a nice cleanup
but with the short time before v5.2 is released this is
probably the best idea, so we can figure out the right way
to do this in the next kernel cycle.

Fixes: 249e2632dcd0 ("spi: gpio: Don't request CS GPIO in DT use-case")
Cc: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

---
 drivers/spi/spi-gpio.c | 137 +++++++++++++++++++++++------------------
 1 file changed, 78 insertions(+), 59 deletions(-)

-- 
2.21.0

Comments

Mark Brown July 2, 2019, 11:35 a.m. | #1
On Mon, Jul 01, 2019 at 07:25:17PM +0200, Linus Walleij wrote:
> This reverts commit 249e2632dcd0509b8f8f296f5aabf4d48dfd6da8.

> 

> After this commit drivers/net/dsa/vitesse-vsc73xx.c stopped


Please use subject lines matching the style for the subsystem.  This
makes it easier for people to identify relevant patches.
Mark Brown July 2, 2019, 11:39 a.m. | #2
On Mon, Jul 01, 2019 at 07:25:17PM +0200, Linus Walleij wrote:
> This reverts commit 249e2632dcd0509b8f8f296f5aabf4d48dfd6da8.

> 

> After this commit drivers/net/dsa/vitesse-vsc73xx.c stopped

> working. Apparently CS is not working because the reads

> from the device is just returning just 1:s or just 0:s at

> all bisection points, so it is a complete regression and

> I think spi-gpio CS is essentially broken.


Also I'm a bit concerned that nobody else noticed this - do we 
have any understanding of what the actual problem is?
Linus Walleij July 2, 2019, 1:08 p.m. | #3
On Tue, Jul 2, 2019 at 1:39 PM Mark Brown <broonie@kernel.org> wrote:
> On Mon, Jul 01, 2019 at 07:25:17PM +0200, Linus Walleij wrote:

> > This reverts commit 249e2632dcd0509b8f8f296f5aabf4d48dfd6da8.

> >

> > After this commit drivers/net/dsa/vitesse-vsc73xx.c stopped

> > working. Apparently CS is not working because the reads

> > from the device is just returning just 1:s or just 0:s at

> > all bisection points, so it is a complete regression and

> > I think spi-gpio CS is essentially broken.

>

> Also I'm a bit concerned that nobody else noticed this - do we

> have any understanding of what the actual problem is?


I am trying to rootcause it, I suspect I was just the first to try this
on real hardware actually.

The users in the device trees in the kernel
mostly point to consumers like LEDs, displays and switches
that wouldn't cause boot regressions
instead you must observe more elaborate aspects of the system
so that is why the automatic test farms cannot see it.

Yours,
Linus Walleij
Linus Walleij July 4, 2019, 7 a.m. | #4
Hi Mark,

the proper fix is now upstream in Torvald's tree so you can drop/revert
this patch.

Yours,
Linus Walleij
Mark Brown July 4, 2019, 11:49 a.m. | #5
On Thu, Jul 04, 2019 at 09:00:17AM +0200, Linus Walleij wrote:
> Hi Mark,

> 

> the proper fix is now upstream in Torvald's tree so you can drop/revert

> this patch.


Great, thanks.

Patch

diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
index eca9d52ecf65..7cf800efef93 100644
--- a/drivers/spi/spi-gpio.c
+++ b/drivers/spi/spi-gpio.c
@@ -36,6 +36,7 @@  struct spi_gpio {
 	struct gpio_desc		*miso;
 	struct gpio_desc		*mosi;
 	struct gpio_desc		**cs_gpios;
+	bool				has_cs;
 };
 
 /*----------------------------------------------------------------------*/
@@ -205,7 +206,7 @@  static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
 		gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
 
 	/* Drive chip select line, if we have one */
-	if (spi_gpio->cs_gpios) {
+	if (spi_gpio->has_cs) {
 		struct gpio_desc *cs = spi_gpio->cs_gpios[spi->chip_select];
 
 		/* SPI chip selects are normally active-low */
@@ -223,12 +224,10 @@  static int spi_gpio_setup(struct spi_device *spi)
 	 * The CS GPIOs have already been
 	 * initialized from the descriptor lookup.
 	 */
-	if (spi_gpio->cs_gpios) {
-		cs = spi_gpio->cs_gpios[spi->chip_select];
-		if (!spi->controller_state && cs)
-			status = gpiod_direction_output(cs,
-						  !(spi->mode & SPI_CS_HIGH));
-	}
+	cs = spi_gpio->cs_gpios[spi->chip_select];
+	if (!spi->controller_state && cs)
+		status = gpiod_direction_output(cs,
+						!(spi->mode & SPI_CS_HIGH));
 
 	if (!status)
 		status = spi_bitbang_setup(spi);
@@ -279,8 +278,12 @@  static void spi_gpio_cleanup(struct spi_device *spi)
  * floating signals.  (A weak pulldown would save power too, but many
  * drivers expect to see all-ones data as the no slave "response".)
  */
-static int spi_gpio_request(struct device *dev, struct spi_gpio *spi_gpio)
+static int spi_gpio_request(struct device *dev,
+			    struct spi_gpio *spi_gpio,
+			    unsigned int num_chipselects)
 {
+	int i;
+
 	spi_gpio->mosi = devm_gpiod_get_optional(dev, "mosi", GPIOD_OUT_LOW);
 	if (IS_ERR(spi_gpio->mosi))
 		return PTR_ERR(spi_gpio->mosi);
@@ -293,6 +296,13 @@  static int spi_gpio_request(struct device *dev, struct spi_gpio *spi_gpio)
 	if (IS_ERR(spi_gpio->sck))
 		return PTR_ERR(spi_gpio->sck);
 
+	for (i = 0; i < num_chipselects; i++) {
+		spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs",
+							     i, GPIOD_OUT_HIGH);
+		if (IS_ERR(spi_gpio->cs_gpios[i]))
+			return PTR_ERR(spi_gpio->cs_gpios[i]);
+	}
+
 	return 0;
 }
 
@@ -303,55 +313,44 @@  static const struct of_device_id spi_gpio_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
 
-static int spi_gpio_probe_dt(struct platform_device *pdev,
-			     struct spi_master *master)
+static int spi_gpio_probe_dt(struct platform_device *pdev)
 {
-	master->dev.of_node = pdev->dev.of_node;
-	master->use_gpio_descriptors = true;
-
-	return 0;
-}
-#else
-static inline int spi_gpio_probe_dt(struct platform_device *pdev,
-				    struct spi_master *master)
-{
-	return 0;
-}
-#endif
-
-static int spi_gpio_probe_pdata(struct platform_device *pdev,
-				struct spi_master *master)
-{
-	struct device *dev = &pdev->dev;
-	struct spi_gpio_platform_data *pdata = dev_get_platdata(dev);
-	struct spi_gpio *spi_gpio = spi_master_get_devdata(master);
-	int i;
+	int ret;
+	u32 tmp;
+	struct spi_gpio_platform_data	*pdata;
+	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *of_id =
+			of_match_device(spi_gpio_dt_ids, &pdev->dev);
 
-#ifdef GENERIC_BITBANG
-	if (!pdata || !pdata->num_chipselect)
-		return -ENODEV;
-#endif
-	/*
-	 * The master needs to think there is a chipselect even if not
-	 * connected
-	 */
-	master->num_chipselect = pdata->num_chipselect ?: 1;
+	if (!of_id)
+		return 0;
 
-	spi_gpio->cs_gpios = devm_kcalloc(dev, master->num_chipselect,
-					  sizeof(*spi_gpio->cs_gpios),
-					  GFP_KERNEL);
-	if (!spi_gpio->cs_gpios)
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
 		return -ENOMEM;
 
-	for (i = 0; i < master->num_chipselect; i++) {
-		spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs", i,
-							     GPIOD_OUT_HIGH);
-		if (IS_ERR(spi_gpio->cs_gpios[i]))
-			return PTR_ERR(spi_gpio->cs_gpios[i]);
+
+	ret = of_property_read_u32(np, "num-chipselects", &tmp);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "num-chipselects property not found\n");
+		goto error_free;
 	}
 
+	pdata->num_chipselect = tmp;
+	pdev->dev.platform_data = pdata;
+
+	return 1;
+
+error_free:
+	devm_kfree(&pdev->dev, pdata);
+	return ret;
+}
+#else
+static inline int spi_gpio_probe_dt(struct platform_device *pdev)
+{
 	return 0;
 }
+#endif
 
 static void spi_gpio_put(void *data)
 {
@@ -363,11 +362,22 @@  static int spi_gpio_probe(struct platform_device *pdev)
 	int				status;
 	struct spi_master		*master;
 	struct spi_gpio			*spi_gpio;
+	struct spi_gpio_platform_data	*pdata;
 	struct device			*dev = &pdev->dev;
 	struct spi_bitbang		*bb;
-	const struct of_device_id	*of_id;
+	bool use_of = 0;
 
-	of_id = of_match_device(spi_gpio_dt_ids, &pdev->dev);
+	status = spi_gpio_probe_dt(pdev);
+	if (status < 0)
+		return status;
+	if (status > 0)
+		use_of = 1;
+
+	pdata = dev_get_platdata(dev);
+#ifdef GENERIC_BITBANG
+	if (!pdata || (!use_of && !pdata->num_chipselect))
+		return -ENODEV;
+#endif
 
 	master = spi_alloc_master(dev, sizeof(*spi_gpio));
 	if (!master)
@@ -377,17 +387,22 @@  static int spi_gpio_probe(struct platform_device *pdev)
 	if (status)
 		return status;
 
-	if (of_id)
-		status = spi_gpio_probe_dt(pdev, master);
-	else
-		status = spi_gpio_probe_pdata(pdev, master);
+	spi_gpio = spi_master_get_devdata(master);
 
-	if (status)
-		return status;
+	spi_gpio->cs_gpios = devm_kcalloc(dev,
+				pdata->num_chipselect,
+				sizeof(*spi_gpio->cs_gpios),
+				GFP_KERNEL);
+	if (!spi_gpio->cs_gpios)
+		return -ENOMEM;
 
-	spi_gpio = spi_master_get_devdata(master);
+	platform_set_drvdata(pdev, spi_gpio);
+
+	/* Determine if we have chip selects connected */
+	spi_gpio->has_cs = !!pdata->num_chipselect;
 
-	status = spi_gpio_request(dev, spi_gpio);
+	status = spi_gpio_request(dev, spi_gpio,
+				  pdata->num_chipselect);
 	if (status)
 		return status;
 
@@ -405,9 +420,13 @@  static int spi_gpio_probe(struct platform_device *pdev)
 	}
 
 	master->bus_num = pdev->id;
+	/* The master needs to think there is a chipselect even if not connected */
+	master->num_chipselect = spi_gpio->has_cs ? pdata->num_chipselect : 1;
 	master->setup = spi_gpio_setup;
 	master->cleanup = spi_gpio_cleanup;
-
+#ifdef CONFIG_OF
+	master->dev.of_node = dev->of_node;
+#endif
 	bb = &spi_gpio->bitbang;
 	bb->master = master;
 	bb->chipselect = spi_gpio_chipselect;