>>> >> so if i understand the code pr_debug code, i see a printk macro assignment, >> >> is it something like printk or a wrapper macro around printk are >> making sure that the strings are non null ? > > Sorry, I don't know how printk deals this null. > > But I tested null by using ams369fg06 driver as below: > > - bd = backlight_device_register("ams369fg06-bl", &spi->dev, lcd, > + bd = backlight_device_register(NULL, &spi->dev, lcd, > > Also, I replaced pr_debug with printk as below: > > - pr_debug("backlight_device_register: name=%s\n", name); > + printk("backlight_device_register: name=%s\n", name); > > In this case, printk message is as below: > > backlight_device_register: name=(null) > >> wow, you tested the code, i would have done it with a single module, great and thanks for lot of information you are putting . >> the documentation of the backlight_device_register says that "name >> must be same as the name of the respected frame buffer device", but do >> we really add a check for the null to do dev_set_name? or fail the >> registering ? > > "name must be same as the name of the respected frame buffer device" is > not correct. Most backlight drivers are using their driver name as 'name'. > > Anyway, in my opinion, deference to null does not seem to happen. > Now, backlight_device_register() calls are using 'name' properly. > > > However, if a check for the null is added, it will be added to > backlight_device_register() as below: > > > @@ -292,6 +292,11 @@ struct backlight_device *backlight_device_register(const char *name, > struct backlight_device *new_bd; > int rc; > > + if (name == NULL) { > + pr_err("....."); > + return -EINVAL > + } > + This is what exactly i was thinking, thanks for making a patch too. If you want to submit it then please take my Acked-By: Devendra Naga <devendra.aaru@xxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html