[PATCH v1 1/5] fbtft: Make sure string is NULL terminated

[PATCH v1 1/5] fbtft: Make sure string is NULL terminated

[Andy Shevchenko]

New GCC warns about inappropriate use of strncpy():

drivers/staging/fbtft/fbtft-core.c: In function ‘fbtft_framebuffer_alloc’:
drivers/staging/fbtft/fbtft-core.c:665:2: warning: ‘strncpy’ specified bound 16 equals destination size [-Wstringop-truncation]
  665 |  strncpy(info->fix.id, dev->driver->name, 16);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Later on the copy is being used with the assumption to be NULL terminated.
Make sure string is NULL terminated by switching to snprintf().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/staging/fbtft/fbtft-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index a0a67aa517f0..61f0286fb157 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -666,7 +666,7 @@ struct fb_info *fbtft_framebuffer_alloc(struct fbtft_display *display,
 	fbdefio->deferred_io =     fbtft_deferred_io;
 	fb_deferred_io_init(info);
 
-	strncpy(info->fix.id, dev->driver->name, 16);
+	snprintf(info->fix.id, sizeof(info->fix.id), "%s", dev->driver->name);
 	info->fix.type =           FB_TYPE_PACKED_PIXELS;
 	info->fix.visual =         FB_VISUAL_TRUECOLOR;
 	info->fix.xpanstep =	   0;
-- 
2.24.0

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[PATCH v1 2/5] fbtft: Describe function parameters in kernel-doc

[Andy Shevchenko]

Kernel documentation script complains that some of the function parameters
are not described:

drivers/staging/fbtft/fbtft-core.c:543: warning: Function parameter or member 'pdata' not described in 'fbtft_framebuffer_alloc'

Describe function parameters where it's appropriate.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/staging/fbtft/fbtft-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 61f0286fb157..2122c4407bdb 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -529,6 +529,7 @@ static void fbtft_merge_fbtftops(struct fbtft_ops *dst, struct fbtft_ops *src)
  *
  * @display: pointer to structure describing the display
  * @dev: pointer to the device for this fb, this can be NULL
+ * @pdata: platform data for the display in use
  *
  * Creates a new frame buffer info structure.
  *
-- 
2.24.0

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[PATCH v1 3/5] fbtft: Drop useless #ifdef CONFIG_OF and dead code

[Andy Shevchenko]

First of all there is no need to guard GPIO request by CONFIG_OF.
It works for everybody independently on resource provider. While here,
rename the function to reflect the above.

Moreover, since we have a global dependency to OF, the rest of
conditional compilation is no-op, i.e. it's always be true.

Due to above drop useless #ifdef CONFIG_OF and therefore dead code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/staging/fbtft/fbtft-core.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 2122c4407bdb..ff8cb6670ea1 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -70,7 +70,6 @@ void fbtft_dbg_hex(const struct device *dev, int groupsize,
 }
 EXPORT_SYMBOL(fbtft_dbg_hex);
 
-#ifdef CONFIG_OF
 static int fbtft_request_one_gpio(struct fbtft_par *par,
 				  const char *name, int index,
 				  struct gpio_desc **gpiop)
@@ -92,14 +91,11 @@ static int fbtft_request_one_gpio(struct fbtft_par *par,
 	return ret;
 }
 
-static int fbtft_request_gpios_dt(struct fbtft_par *par)
+static int fbtft_request_gpios(struct fbtft_par *par)
 {
 	int i;
 	int ret;
 
-	if (!par->info->device->of_node)
-		return -EINVAL;
-
 	ret = fbtft_request_one_gpio(par, "reset", 0, &par->gpio.reset);
 	if (ret)
 		return ret;
@@ -135,7 +131,6 @@ static int fbtft_request_gpios_dt(struct fbtft_par *par)
 
 	return 0;
 }
-#endif
 
 #ifdef CONFIG_FB_BACKLIGHT
 static int fbtft_backlight_update_status(struct backlight_device *bd)
@@ -898,7 +893,6 @@ int fbtft_unregister_framebuffer(struct fb_info *fb_info)
 }
 EXPORT_SYMBOL(fbtft_unregister_framebuffer);
 
-#ifdef CONFIG_OF
 /**
  * fbtft_init_display_dt() - Device Tree init_display() function
  * @par: Driver data
@@ -977,7 +971,6 @@ static int fbtft_init_display_dt(struct fbtft_par *par)
 
 	return 0;
 }
-#endif
 
 /**
  * fbtft_init_display() - Generic init_display() function
@@ -1138,7 +1131,6 @@ static int fbtft_verify_gpios(struct fbtft_par *par)
 	return 0;
 }
 
-#ifdef CONFIG_OF
 /* returns 0 if the property is not present */
 static u32 fbtft_of_value(struct device_node *node, const char *propname)
 {
@@ -1184,17 +1176,10 @@ static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
 		pdata->display.backlight = 1;
 	if (of_find_property(node, "init", NULL))
 		pdata->display.fbtftops.init_display = fbtft_init_display_dt;
-	pdata->display.fbtftops.request_gpios = fbtft_request_gpios_dt;
+	pdata->display.fbtftops.request_gpios = fbtft_request_gpios;
 
 	return pdata;
 }
-#else
-static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
-{
-	dev_err(dev, "Missing platform data\n");
-	return ERR_PTR(-EINVAL);
-}
-#endif
 
 /**
  * fbtft_probe_common() - Generic device probe() helper function
-- 
2.24.0

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[PATCH v1 4/5] fbtft: Make use of device property API

[Andy Shevchenko]

Make use of device property API in this driver so that both OF based
system and ACPI based system can use this driver.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/staging/fbtft/fbtft-core.c | 105 ++++++++++++++++-------------
 1 file changed, 58 insertions(+), 47 deletions(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index ff8cb6670ea1..e87d839d86ac 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -22,8 +22,9 @@
 #include <linux/uaccess.h>
 #include <linux/backlight.h>
 #include <linux/platform_device.h>
+#include <linux/property.h>
 #include <linux/spinlock.h>
-#include <linux/of.h>
+
 #include <video/mipi_display.h>
 
 #include "fbtft.h"
@@ -894,44 +895,53 @@ int fbtft_unregister_framebuffer(struct fb_info *fb_info)
 EXPORT_SYMBOL(fbtft_unregister_framebuffer);
 
 /**
- * fbtft_init_display_dt() - Device Tree init_display() function
+ * fbtft_init_display_from_property() - Device Tree init_display() function
  * @par: Driver data
  *
  * Return: 0 if successful, negative if error
  */
-static int fbtft_init_display_dt(struct fbtft_par *par)
+static int fbtft_init_display_from_property(struct fbtft_par *par)
 {
-	struct device_node *node = par->info->device->of_node;
-	struct property *prop;
-	const __be32 *p;
+	struct device *dev = par->info->device;
+	int buf[64], count, index, i, j, ret;
+	u32 *values;
 	u32 val;
-	int buf[64], i, j;
 
-	if (!node)
+	count = device_property_count_u32(dev, "init");
+	if (count < 0)
+		return count;
+	if (count == 0)
 		return -EINVAL;
 
-	prop = of_find_property(node, "init", NULL);
-	p = of_prop_next_u32(prop, NULL, &val);
-	if (!p)
-		return -EINVAL;
+	values = kmalloc_array(count, sizeof(*values), GFP_KERNEL);
+	if (!values)
+		return -ENOMEM;
+
+	ret = device_property_read_u32_array(dev, "init", values, count);
+	if (ret)
+		goto out_free;
 
 	par->fbtftops.reset(par);
 	if (par->gpio.cs)
 		gpiod_set_value(par->gpio.cs, 0);  /* Activate chip */
 
-	while (p) {
+	index = -1;
+	while (index < count) {
+		val = values[++index];
+
 		if (val & FBTFT_OF_INIT_CMD) {
 			val &= 0xFFFF;
 			i = 0;
-			while (p && !(val & 0xFFFF0000)) {
+			while ((index < count) && !(val & 0xFFFF0000)) {
 				if (i > 63) {
-					dev_err(par->info->device,
+					dev_err(dev,
 						"%s: Maximum register values exceeded\n",
 						__func__);
-					return -EINVAL;
+					ret = -EINVAL;
+					goto out_free;
 				}
 				buf[i++] = val;
-				p = of_prop_next_u32(prop, p, &val);
+				val = values[++index];
 			}
 			/* make debug message */
 			fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
@@ -961,15 +971,17 @@ static int fbtft_init_display_dt(struct fbtft_par *par)
 			fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
 				      "init: msleep(%u)\n", val & 0xFFFF);
 			msleep(val & 0xFFFF);
-			p = of_prop_next_u32(prop, p, &val);
+			val = values[++index];
 		} else {
-			dev_err(par->info->device, "illegal init value 0x%X\n",
-				val);
-			return -EINVAL;
+			dev_err(dev, "illegal init value 0x%X\n", val);
+			ret = -EINVAL;
+			goto out_free;
 		}
 	}
 
-	return 0;
+out_free:
+	kfree(values);
+	return ret;
 }
 
 /**
@@ -1132,25 +1144,24 @@ static int fbtft_verify_gpios(struct fbtft_par *par)
 }
 
 /* returns 0 if the property is not present */
-static u32 fbtft_of_value(struct device_node *node, const char *propname)
+static u32 fbtft_property_value(struct device *dev, const char *propname)
 {
 	int ret;
 	u32 val = 0;
 
-	ret = of_property_read_u32(node, propname, &val);
+	ret = device_property_read_u32(dev, propname, &val);
 	if (ret == 0)
-		pr_info("%s: %s = %u\n", __func__, propname, val);
+		dev_info(dev, "%s: %s = %u\n", __func__, propname, val);
 
 	return val;
 }
 
-static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
+static struct fbtft_platform_data *fbtft_properties_read(struct device *dev)
 {
-	struct device_node *node = dev->of_node;
 	struct fbtft_platform_data *pdata;
 
-	if (!node) {
-		dev_err(dev, "Missing platform data or DT\n");
+	if (!dev_fwnode(dev)) {
+		dev_err(dev, "Missing platform data or properties\n");
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -1158,24 +1169,24 @@ static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);
 
-	pdata->display.width = fbtft_of_value(node, "width");
-	pdata->display.height = fbtft_of_value(node, "height");
-	pdata->display.regwidth = fbtft_of_value(node, "regwidth");
-	pdata->display.buswidth = fbtft_of_value(node, "buswidth");
-	pdata->display.backlight = fbtft_of_value(node, "backlight");
-	pdata->display.bpp = fbtft_of_value(node, "bpp");
-	pdata->display.debug = fbtft_of_value(node, "debug");
-	pdata->rotate = fbtft_of_value(node, "rotate");
-	pdata->bgr = of_property_read_bool(node, "bgr");
-	pdata->fps = fbtft_of_value(node, "fps");
-	pdata->txbuflen = fbtft_of_value(node, "txbuflen");
-	pdata->startbyte = fbtft_of_value(node, "startbyte");
-	of_property_read_string(node, "gamma", (const char **)&pdata->gamma);
-
-	if (of_find_property(node, "led-gpios", NULL))
+	pdata->display.width = fbtft_property_value(dev, "width");
+	pdata->display.height = fbtft_property_value(dev, "height");
+	pdata->display.regwidth = fbtft_property_value(dev, "regwidth");
+	pdata->display.buswidth = fbtft_property_value(dev, "buswidth");
+	pdata->display.backlight = fbtft_property_value(dev, "backlight");
+	pdata->display.bpp = fbtft_property_value(dev, "bpp");
+	pdata->display.debug = fbtft_property_value(dev, "debug");
+	pdata->rotate = fbtft_property_value(dev, "rotate");
+	pdata->bgr = device_property_read_bool(dev, "bgr");
+	pdata->fps = fbtft_property_value(dev, "fps");
+	pdata->txbuflen = fbtft_property_value(dev, "txbuflen");
+	pdata->startbyte = fbtft_property_value(dev, "startbyte");
+	device_property_read_string(dev, "gamma", (const char **)&pdata->gamma);
+
+	if (device_property_present(dev, "led-gpios"))
 		pdata->display.backlight = 1;
-	if (of_find_property(node, "init", NULL))
-		pdata->display.fbtftops.init_display = fbtft_init_display_dt;
+	if (device_property_present(dev, "init"))
+		pdata->display.fbtftops.init_display = fbtft_init_display_from_property;
 	pdata->display.fbtftops.request_gpios = fbtft_request_gpios;
 
 	return pdata;
@@ -1213,7 +1224,7 @@ int fbtft_probe_common(struct fbtft_display *display,
 
 	pdata = dev->platform_data;
 	if (!pdata) {
-		pdata = fbtft_probe_dt(dev);
+		pdata = fbtft_properties_read(dev);
 		if (IS_ERR(pdata))
 			return PTR_ERR(pdata);
 	}
-- 
2.24.0

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[PATCH v1 5/5] fbtft: Drop OF dependency

[Andy Shevchenko]

Now, since driver became OF independent, no need to keep OF dependency.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/staging/fbtft/Kconfig | 2 +-
 drivers/staging/fbtft/fbtft.h | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/fbtft/Kconfig b/drivers/staging/fbtft/Kconfig
index cb61c2a772bd..54751d9fc0ff 100644
--- a/drivers/staging/fbtft/Kconfig
+++ b/drivers/staging/fbtft/Kconfig
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 menuconfig FB_TFT
 	tristate "Support for small TFT LCD display modules"
-	depends on FB && SPI && OF
+	depends on FB && SPI
 	depends on GPIOLIB || COMPILE_TEST
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
diff --git a/drivers/staging/fbtft/fbtft.h b/drivers/staging/fbtft/fbtft.h
index 9b6bdb62093d..5f782da51959 100644
--- a/drivers/staging/fbtft/fbtft.h
+++ b/drivers/staging/fbtft/fbtft.h
@@ -309,7 +309,7 @@ MODULE_DEVICE_TABLE(of, dt_ids);                                           \
 static struct spi_driver fbtft_driver_spi_driver = {                       \
 	.driver = {                                                        \
 		.name   = _name,                                           \
-		.of_match_table = of_match_ptr(dt_ids),                    \
+		.of_match_table = dt_ids,                                  \
 	},                                                                 \
 	.probe  = fbtft_driver_probe_spi,                                  \
 	.remove = fbtft_driver_remove_spi,                                 \
@@ -319,7 +319,7 @@ static struct platform_driver fbtft_driver_platform_driver = {             \
 	.driver = {                                                        \
 		.name   = _name,                                           \
 		.owner  = THIS_MODULE,                                     \
-		.of_match_table = of_match_ptr(dt_ids),                    \
+		.of_match_table = dt_ids,                                  \
 	},                                                                 \
 	.probe  = fbtft_driver_probe_pdev,                                 \
 	.remove = fbtft_driver_remove_pdev,                                \
-- 
2.24.0

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Re: [PATCH v1 3/5] fbtft: Drop useless #ifdef CONFIG_OF and dead code

[Noralf Trønnes]

Den 20.11.2019 10.57, skrev Andy Shevchenko:
> First of all there is no need to guard GPIO request by CONFIG_OF.
> It works for everybody independently on resource provider. While here,
> rename the function to reflect the above.
> 
> Moreover, since we have a global dependency to OF, the rest of
> conditional compilation is no-op, i.e. it's always be true.
> 
> Due to above drop useless #ifdef CONFIG_OF and therefore dead code.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/staging/fbtft/fbtft-core.c | 19 ++-----------------
>  1 file changed, 2 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c

<snip>

> @@ -1184,17 +1176,10 @@ static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
>  		pdata->display.backlight = 1;
>  	if (of_find_property(node, "init", NULL))
>  		pdata->display.fbtftops.init_display = fbtft_init_display_dt;
> -	pdata->display.fbtftops.request_gpios = fbtft_request_gpios_dt;
> +	pdata->display.fbtftops.request_gpios = fbtft_request_gpios;

You can ditch the .request_gpios callback and call fbtft_request_gpios()
directly in fbtft_register_framebuffer(). That will make it safe to drop
the OF dependency, otherwise .request_gpios will be NULL in the non-DT
case. This is one of the bugs that follwed the gpio refactoring.

You can also ditch the .request_gpios_match callback if you want, it
isn't called anymore (it is set in fb_agm1264k-fl).

Noralf.

>  
>  	return pdata;
>  }
> -#else
> -static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
> -{
> -	dev_err(dev, "Missing platform data\n");
> -	return ERR_PTR(-EINVAL);
> -}
> -#endif
>  
>  /**
>   * fbtft_probe_common() - Generic device probe() helper function
> 
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Re: [PATCH v1 3/5] fbtft: Drop useless #ifdef CONFIG_OF and dead code

[Noralf Trønnes]

Den 20.11.2019 15.43, skrev Noralf Trønnes:
> 
> 
> Den 20.11.2019 10.57, skrev Andy Shevchenko:
>> First of all there is no need to guard GPIO request by CONFIG_OF.
>> It works for everybody independently on resource provider. While here,
>> rename the function to reflect the above.
>>
>> Moreover, since we have a global dependency to OF, the rest of
>> conditional compilation is no-op, i.e. it's always be true.
>>
>> Due to above drop useless #ifdef CONFIG_OF and therefore dead code.
>>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>> ---
>>  drivers/staging/fbtft/fbtft-core.c | 19 ++-----------------
>>  1 file changed, 2 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> 
> <snip>
> 
>> @@ -1184,17 +1176,10 @@ static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
>>  		pdata->display.backlight = 1;
>>  	if (of_find_property(node, "init", NULL))
>>  		pdata->display.fbtftops.init_display = fbtft_init_display_dt;
>> -	pdata->display.fbtftops.request_gpios = fbtft_request_gpios_dt;
>> +	pdata->display.fbtftops.request_gpios = fbtft_request_gpios;
> 
> You can ditch the .request_gpios callback and call fbtft_request_gpios()
> directly in fbtft_register_framebuffer(). That will make it safe to drop
> the OF dependency, otherwise .request_gpios will be NULL in the non-DT
> case. This is one of the bugs that follwed the gpio refactoring.

Really difficult to read this fbtft code (that I wrote...).
The NULL deref can only happen when dev->platform_data is set. That
can't happen, in mainline at least, now that fbtft_device is gone.

> 
> You can also ditch the .request_gpios_match callback if you want, it
> isn't called anymore (it is set in fb_agm1264k-fl).
> 
> Noralf.
> 
>>  
>>  	return pdata;
>>  }
>> -#else
>> -static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
>> -{
>> -	dev_err(dev, "Missing platform data\n");
>> -	return ERR_PTR(-EINVAL);
>> -}
>> -#endif
>>  
>>  /**
>>   * fbtft_probe_common() - Generic device probe() helper function
>>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
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Re: [PATCH v1 3/5] fbtft: Drop useless #ifdef CONFIG_OF and dead code

[Andy Shevchenko]

On Wed, Nov 20, 2019 at 04:04:17PM +0100, Noralf Trønnes wrote:
> Den 20.11.2019 15.43, skrev Noralf Trønnes:
> > Den 20.11.2019 10.57, skrev Andy Shevchenko:

> >> First of all there is no need to guard GPIO request by CONFIG_OF.
> >> It works for everybody independently on resource provider. While here,
> >> rename the function to reflect the above.
> >>
> >> Moreover, since we have a global dependency to OF, the rest of
> >> conditional compilation is no-op, i.e. it's always be true.
> >>
> >> Due to above drop useless #ifdef CONFIG_OF and therefore dead code.
> >>
> >> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >> ---
> >>  drivers/staging/fbtft/fbtft-core.c | 19 ++-----------------
> >>  1 file changed, 2 insertions(+), 17 deletions(-)
> >>
> >> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> > 
> > <snip>
> > 
> >> @@ -1184,17 +1176,10 @@ static struct fbtft_platform_data *fbtft_probe_dt(struct device *dev)
> >>  		pdata->display.backlight = 1;
> >>  	if (of_find_property(node, "init", NULL))
> >>  		pdata->display.fbtftops.init_display = fbtft_init_display_dt;
> >> -	pdata->display.fbtftops.request_gpios = fbtft_request_gpios_dt;
> >> +	pdata->display.fbtftops.request_gpios = fbtft_request_gpios;
> > 
> > You can ditch the .request_gpios callback and call fbtft_request_gpios()
> > directly in fbtft_register_framebuffer(). That will make it safe to drop
> > the OF dependency, otherwise .request_gpios will be NULL in the non-DT
> > case. This is one of the bugs that follwed the gpio refactoring.
> 
> Really difficult to read this fbtft code (that I wrote...).
> The NULL deref can only happen when dev->platform_data is set. That
> can't happen, in mainline at least, now that fbtft_device is gone.

Hmm... If I read code correctly this patch doesn't change this logic. We have
non-NULL ->request_gpios() in case of pdata != NULL if and only if supplier
gives it to us.

The above assignment happens only for DT case (fbtft_properties_read() is
guarded against non-DT, okay non-fwnode, cases).

> > You can also ditch the .request_gpios_match callback if you want, it
> > isn't called anymore (it is set in fb_agm1264k-fl).

I guess both improvements can be done later since they are not affecting the
logic in this series.

-- 
With Best Regards,
Andy Shevchenko


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Re: [PATCH v1 1/5] fbtft: Make sure string is NULL terminated

[Steven Price]

On 20/11/2019 09:57, Andy Shevchenko wrote:
> New GCC warns about inappropriate use of strncpy():
> 
> drivers/staging/fbtft/fbtft-core.c: In function ‘fbtft_framebuffer_alloc’:
> drivers/staging/fbtft/fbtft-core.c:665:2: warning: ‘strncpy’ specified bound 16 equals destination size [-Wstringop-truncation]
>   665 |  strncpy(info->fix.id, dev->driver->name, 16);
>       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Later on the copy is being used with the assumption to be NULL terminated.
> Make sure string is NULL terminated by switching to snprintf().

Even better would be strscpy():

	strscpy(info->fix.id, dev->driver->name, sizeof(info->fix.id));

Steve

> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/staging/fbtft/fbtft-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> index a0a67aa517f0..61f0286fb157 100644
> --- a/drivers/staging/fbtft/fbtft-core.c
> +++ b/drivers/staging/fbtft/fbtft-core.c
> @@ -666,7 +666,7 @@ struct fb_info *fbtft_framebuffer_alloc(struct fbtft_display *display,
>  	fbdefio->deferred_io =     fbtft_deferred_io;
>  	fb_deferred_io_init(info);
>  
> -	strncpy(info->fix.id, dev->driver->name, 16);
> +	snprintf(info->fix.id, sizeof(info->fix.id), "%s", dev->driver->name);
>  	info->fix.type =           FB_TYPE_PACKED_PIXELS;
>  	info->fix.visual =         FB_VISUAL_TRUECOLOR;
>  	info->fix.xpanstep =	   0;
> 

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