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Message-ID: <20150207174244.25987977@maestro.intranet>
Date: Sat, 7 Feb 2015 17:42:44 +0100
From: Thomas Niederprüm <niederp@...sik.uni-kl.de>
To: Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc: linux-fbdev@...r.kernel.org, plagnioj@...osoft.com,
tomi.valkeinen@...com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/8] fbdev: ssd1307fb: Add sysfs handles to expose
contrast and dim setting to userspace.
Am Sat, 7 Feb 2015 12:43:29 +0100
schrieb Maxime Ripard <maxime.ripard@...e-electrons.com>:
> On Fri, Feb 06, 2015 at 11:28:13PM +0100, niederp@...sik.uni-kl.de
> wrote:
> > From: Thomas Niederprüm <niederp@...sik.uni-kl.de>
> >
> > This patch adds sysfs handles to enable userspace control over the
> > display contrast as well as the dim mode. The handles are available
> > as "contrast" and "dim" in the framebuffers sysfs domain.
> >
> > Signed-off-by: Thomas Niederprüm <niederp@...sik.uni-kl.de>
> > ---
> > drivers/video/fbdev/ssd1307fb.c | 88
> > ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 87
> > insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/video/fbdev/ssd1307fb.c
> > b/drivers/video/fbdev/ssd1307fb.c index b38315d..02931c7 100644
> > --- a/drivers/video/fbdev/ssd1307fb.c
> > +++ b/drivers/video/fbdev/ssd1307fb.c
> > @@ -33,6 +33,7 @@
> > #define SSD1307FB_CONTRAST 0x81
> > #define SSD1307FB_CHARGE_PUMP 0x8d
> > #define SSD1307FB_SEG_REMAP_ON 0xa1
> > +#define SSD1307FB_DISPLAY_DIM 0xac
> > #define SSD1307FB_DISPLAY_OFF 0xae
> > #define SSD1307FB_SET_MULTIPLEX_RATIO 0xa8
> > #define SSD1307FB_DISPLAY_ON 0xaf
> > @@ -43,6 +44,9 @@
> > #define SSD1307FB_SET_COM_PINS_CONFIG 0xda
> > #define SSD1307FB_SET_VCOMH 0xdb
> >
> > +#define MIN_CONTRAST 0
> > +#define MAX_CONTRAST 255
> > +
> > #define BITSPERPIXEL 1
> > #define DELAYDIVIDER 20
> >
> > @@ -69,6 +73,7 @@ struct ssd1307fb_par {
> > u32 dclk_div;
> > u32 dclk_frq;
> > struct ssd1307fb_deviceinfo *device_info;
> > + u32 dim;
> > struct i2c_client *client;
> > u32 height;
> > struct fb_info *info;
> > @@ -515,6 +520,79 @@ static const struct of_device_id
> > ssd1307fb_of_match[] = { };
> > MODULE_DEVICE_TABLE(of, ssd1307fb_of_match);
> >
> > +static ssize_t show_contrast(struct device *device,
> > + struct device_attribute *attr, char
> > *buf) +{
> > + struct fb_info *info = dev_get_drvdata(device);
> > + struct ssd1307fb_par *par = info->par;
> > +
> > + return snprintf(buf, PAGE_SIZE, "%d\n", par->contrast);
> > +}
> > +
> > +static ssize_t store_contrast(struct device *device,
> > + struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct fb_info *info = dev_get_drvdata(device);
> > + struct ssd1307fb_par *par = info->par;
> > + unsigned long contrastval;
> > + int ret;
> > +
> > + ret = kstrtoul(buf, 0, &contrastval);
> > + if (ret < 0)
> > + return ret;
> > +
> > + par->contrast = max(min(contrastval,
> > + (ulong)MAX_CONTRAST), (ulong)MIN_CONTRAST);
> > +
> > + ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CONTRAST);
> > + ret = ret & ssd1307fb_write_cmd(par->client,
> > par->contrast);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return count;
> > +}
> > +
> > +
> > +static ssize_t show_dim(struct device *device,
> > + struct device_attribute *attr, char
> > *buf) +{
> > + struct fb_info *info = dev_get_drvdata(device);
> > + struct ssd1307fb_par *par = info->par;
> > +
> > + return snprintf(buf, PAGE_SIZE, "%d\n", par->dim);
> > +}
> > +
> > +static ssize_t store_dim(struct device *device,
> > + struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct fb_info *info = dev_get_drvdata(device);
> > + struct ssd1307fb_par *par = info->par;
> > + unsigned long dimval;
> > + int ret;
> > +
> > + ret = kstrtoul(buf, 0, &dimval);
> > + if (ret < 0)
> > + return ret;
> > +
> > + par->dim = max(min(dimval, (ulong)1), (ulong)0);
> > + if (par->dim)
> > + ret = ssd1307fb_write_cmd(par->client,
> > SSD1307FB_DISPLAY_DIM);
> > + else
> > + ret = ssd1307fb_write_cmd(par->client,
> > SSD1307FB_DISPLAY_ON);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return count;
> > +}
> > +
> > +static struct device_attribute device_attrs[] = {
> > + __ATTR(contrast, S_IRUGO|S_IWUSR, show_contrast,
> > store_contrast),
> > + __ATTR(dim, S_IRUGO|S_IWUSR, show_dim, store_dim),
> > +
> > +};
> > +
>
> I would have thought this was something accessible through the
> framebuffer ioctl.
>
> Apparently it's not, at least for the contrast, so maybe it should be
> added there, instead of doing it for a single driver?
I think the contrast setting for an OLED display is much like the
backlight setting for LCD panel. Since there is also no ioctl to set
the backlight of an LCD I wonder if the contrast of an OLED should have
one.
>
> (oh, and btw, every sysfs file should be documented in
> Documentation/ABI)
>
> > static int ssd1307fb_probe(struct i2c_client *client,
> > const struct i2c_device_id *id)
> > {
> > @@ -523,7 +601,7 @@ static int ssd1307fb_probe(struct i2c_client
> > *client, u32 vmem_size;
> > struct ssd1307fb_par *par;
> > u8 *vmem;
> > - int ret;
> > + int ret, i;
> >
> > if (!node) {
> > dev_err(&client->dev, "No device tree data
> > found!\n"); @@ -650,6 +728,14 @@ static int ssd1307fb_probe(struct
> > i2c_client *client, goto reset_oled_error;
> >
> > ret = register_framebuffer(info);
> > +
> > + for (i = 0; i < ARRAY_SIZE(device_attrs); i++)
> > + ret = device_create_file(info->dev,
> > &device_attrs[i]); +
> > + if (ret) {
> > + dev_err(&client->dev, "Couldn't register sysfs
> > nodes\n");
> > + }
> > +
>
> sysfs_create_groups does pretty much that already.
I'll have a look at it.
>
> And don't forget to remove these files in the .remove()
Good point! :)
>
> > if (ret) {
> > dev_err(&client->dev, "Couldn't register the
> > framebuffer\n"); goto panel_init_error;
> > --
> > 2.1.1
> >
>
> Maxime
>
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