diff options
| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2021-05-03 20:21:10 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-10 12:19:39 +0300 |
| commit | ec03c2104365ead0a33627c05e685093eed3eaef (patch) | |
| tree | 4ab8bc52ee8a98a5d581f1dddf012398fff5f6ef /drivers/staging/fbtft/fb_ssd1289.c | |
| parent | 0d59ca5a7ed1195feacc99560f91004d334aa4a9 (diff) | |
| download | linux-ec03c2104365ead0a33627c05e685093eed3eaef.tar.xz | |
staging: fbtft: Rectify GPIO handling
The infamous commit c440eee1a7a1 ("Staging: staging: fbtft: Switch to
the GPIO descriptor interface") broke GPIO handling completely.
It has already four commits to rectify and it seems not enough.
In order to fix the mess here we:
1) Set default to "inactive" for all requested pins
2) Fix CS#, RD#, and WR# pins polarity since it's active low
and GPIO descriptor interface takes it into consideration
from the Device Tree or ACPI
3) Consolidate chip activation (CS# assertion) under default
->reset() callback
To summarize the expectations about polarity for GPIOs:
RD# Low
WR# Low
CS# Low
RESET# Low
DC or RS High
RW High
Data 0 .. 15 High
See also Adafruit learning course [1] for the example of the schematics.
While at it, drop unneeded NULL checks, since GPIO API is tolerant to that.
[1]: https://learn.adafruit.com/adafruit-2-8-and-3-2-color-tft-touchscreen-breakout-v2/downloads
Fixes: 92e3e884887c ("Staging: fbtft: Fix GPIO handling")
Fixes: b918d1c27066 ("Staging: fbtft: Fix reset assertion when using gpio descriptor")
Fixes: dbc4f989c878 ("Staging: fbtft: Fix probing of gpio descriptor")
Fixes: c440eee1a7a1 ("Staging: fbtft: Switch to the gpio descriptor interface")
Cc: Jan Sebastian Götte <linux@jaseg.net>
Cc: Nishad Kamdar <nishadkamdar@gmail.com>
Reviewed-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210503172114.27891-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/fbtft/fb_ssd1289.c')
| -rw-r--r-- | drivers/staging/fbtft/fb_ssd1289.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/drivers/staging/fbtft/fb_ssd1289.c b/drivers/staging/fbtft/fb_ssd1289.c index 7a3fe022cc69..f27bab38b3ec 100644 --- a/drivers/staging/fbtft/fb_ssd1289.c +++ b/drivers/staging/fbtft/fb_ssd1289.c @@ -10,7 +10,6 @@ #include <linux/module.h> #include <linux/kernel.h> #include <linux/init.h> -#include <linux/gpio/consumer.h> #include "fbtft.h" @@ -28,9 +27,6 @@ static int init_display(struct fbtft_par *par) { par->fbtftops.reset(par); - if (par->gpio.cs) - gpiod_set_value(par->gpio.cs, 0); /* Activate chip */ - write_reg(par, 0x00, 0x0001); write_reg(par, 0x03, 0xA8A4); write_reg(par, 0x0C, 0x0000); |