RE: [PATCH V2 3/7] ARM: EXYNOS5: add machine specific support for LCD

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hello,

On Thursday, July 19, 2012 3:22 PM Leela Krishna Amudala wrote:

> Hello Marek,
> 
> On Wed, Jul 18, 2012 at 12:15 PM, Marek Szyprowski
> <m.szyprowski@samsung.com> wrote:
> > Hello,
> >
> > On Wednesday, July 18, 2012 7:57 AM Leela Krishna Amudala wrote:
> >
> >> This patch adds machine specific support for LCD controller like setting power to LCD
> >> and adding LCD platform device.
> >>
> >> Signed-off-by: Prathyush K <prathyush.k@samsung.com>
> >> Signed-off-by: Leela Krishna Amudala <l.krishna@samsung.com>
> >> ---
> >>  arch/arm/mach-exynos/mach-exynos5-dt.c |   56 ++++++++++++++++++++++++++++++++
> >>  1 files changed, 56 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/arch/arm/mach-exynos/mach-exynos5-dt.c b/arch/arm/mach-exynos/mach-exynos5-
> dt.c
> >> index e7113cc..02a0e68 100644
> >> --- a/arch/arm/mach-exynos/mach-exynos5-dt.c
> >> +++ b/arch/arm/mach-exynos/mach-exynos5-dt.c
> >> @@ -13,6 +13,7 @@
> >>  #include <linux/serial_core.h>
> >>  #include <linux/pwm_backlight.h>
> >>  #include <linux/gpio.h>
> >> +#include <linux/delay.h>
> >>
> >>  #include <asm/mach/arch.h>
> >>  #include <asm/hardware/gic.h>
> >> @@ -24,6 +25,7 @@
> >>  #include <plat/gpio-cfg.h>
> >>
> >>  #include "common.h"
> >> +#include <video/platform_lcd.h>
> >>
> >>  static int smdk5250_bl_notify(struct device *unused, int brightness)
> >>  {
> >> @@ -47,6 +49,55 @@ static struct platform_pwm_backlight_data smdk5250_bl_data = {
> >>       .notify         = smdk5250_bl_notify,
> >>  };
> >>
> >> +static void lcd_set_power(struct plat_lcd_data *pd,
> >> +                     unsigned int power)
> >> +{
> >> +
> >> +     /* reset */
> >> +     gpio_request_one(EXYNOS5_GPX1(5), GPIOF_OUT_INIT_HIGH, "GPX1");
> >> +
> >> +     mdelay(20);
> >> +     if (power) {
> >> +             /* fire nRESET on power up */
> >> +             gpio_set_value(EXYNOS5_GPX1(5), 0);
> >> +             mdelay(20);
> >> +             gpio_set_value(EXYNOS5_GPX1(5), 1);
> >> +             mdelay(20);
> >> +             gpio_free(EXYNOS5_GPX1(5));
> >> +     } else {
> >> +             /* fire nRESET on power off */
> >> +             gpio_set_value(EXYNOS5_GPX1(5), 0);
> >> +             mdelay(20);
> >> +             gpio_set_value(EXYNOS5_GPX1(5), 1);
> >> +             mdelay(20);
> >> +             gpio_free(EXYNOS5_GPX1(5));
> >> +     }
> >> +     mdelay(20);
> >> +
> >> +     /*
> >> +      * Request lcd_bl_en GPIO for smdk5250_bl_notify().
> >> +      * TODO: Fix this so we are not at risk of requesting the GPIO
> >> +      * multiple times, this should be done with device tree, and
> >> +      * likely integrated into the plat-samsung/dev-backlight.c init.
> >> +      */
> >> +     gpio_request_one(EXYNOS5_GPX3(0), GPIOF_OUT_INIT_LOW, "GPX3");
> >> +}
> >> +
> >> +static int smdk5250_match_fb(struct plat_lcd_data *pd, struct fb_info *info)
> >> +{
> >> +     /* Don't call .set_power callback while unblanking */
> >> +     return 0;
> >> +}
> >> +
> >> +static struct plat_lcd_data smdk5250_lcd_data = {
> >> +     .set_power      = lcd_set_power,
> >> +     .match_fb       = smdk5250_match_fb,
> >> +};
> >> +
> >> +static struct platform_device smdk5250_lcd = {
> >> +     .name                   = "platform-lcd",
> >> +     .dev.platform_data      = &smdk5250_lcd_data,
> >> +};
> >>  /*
> >>   * The following lookup table is used to override device names when devices
> >>   * are registered from device tree. This is temporarily added to enable
> >> @@ -85,6 +136,10 @@ static const struct of_dev_auxdata exynos5250_auxdata_lookup[]
> __initconst
> >> = {
> >>       {},
> >>  };
> >>
> >> +static struct platform_device *smdk5250_devices[] __initdata = {
> >> +     &smdk5250_lcd, /* for platform_lcd device */
> >> +};
> >> +
> >>  static void __init exynos5250_dt_map_io(void)
> >>  {
> >>       exynos_init_io(NULL, 0);
> >> @@ -96,6 +151,7 @@ static void __init exynos5250_dt_machine_init(void)
> >>       samsung_bl_set(&smdk5250_bl_gpio_info, &smdk5250_bl_data);
> >>       of_platform_populate(NULL, of_default_bus_match_table,
> >>                               exynos5250_auxdata_lookup, NULL);
> >> +     platform_add_devices(smdk5250_devices, ARRAY_SIZE(smdk5250_devices));
> >>  }
> >>
> >>  static char const *exynos5250_dt_compat[] __initdata = {
> >
> > Sorry, but this patch looks completely weird to me. exynos5-dt machine is aimed to
> > operate on ANY Exynos5 based board with proper device tree bindings, not only SMDK5250.
> > Please add DT support to platform lcd driver and create required bindings for it
> > instead of hardcoding the platform data and gpio numbers in mach-exynos5-dt.c
> >
> 
> Yes true, that GPIO numbers will vary for boards.
> Can you please confirm that platform lcd driver means the core
> "drivers/video/backlight/platform_lcd.c" file.

Yes, by lcd driver I meant that driver.

> But platform lcd driver is used by other(non samsung) platforms also.
> So, If I add the DT suppot to that file, I have to test the changes on
> other platforms also.
> Can you please kindly suggest me some other way to overcome this situation.

Just check that you don't break existing code. For some examples please refer to the DT
changes in drivers/input/keyboard/gpio_keys.c (see commit fd05d08920). You can also check
if the driver works fine after your changes by setting it up from platform data instead of
DT.

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center