linux-kernel - [PATCHv4 07/10] fbdev: ssd1307fb: Add a module parameter to set the refresh rate

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Message-Id: <1426525918-12745-8-git-send-email-niederp@physik.uni-kl.de>
Date:	Mon, 16 Mar 2015 18:11:55 +0100
From:	Thomas Niederprüm <niederp@...sik.uni-kl.de>
To:	plagnioj@...osoft.com, tomi.valkeinen@...com,
	maxime.ripard@...e-electrons.com, kernel@...gutronix.de,
	shawn.guo@...aro.org, robh+dt@...nel.org
Cc:	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Niederprüm <niederp@...sik.uni-kl.de>
Subject: [PATCHv4 07/10] fbdev: ssd1307fb: Add a module parameter to set the refresh rate

This patch adds the module parameter "refreshrate" to set delay for the
deferred io. The refresh rate is given in units of Hertz. The default
refresh rate is 1 Hz. The refresh rate set through the newly introduced
parameter applies to all instances of the driver and for now it is not
possible to change it individually.

Signed-off-by: Thomas Niederprüm <niederp@...sik.uni-kl.de>
---
 drivers/video/fbdev/ssd1307fb.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 6fecec8..8a8d305 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -42,6 +42,11 @@
 #define	SSD1307FB_SET_COM_PINS_CONFIG	0xda
 #define	SSD1307FB_SET_VCOMH		0xdb
 
+#define REFRASHRATE 1
+
+static u_int refreshrate = REFRASHRATE;
+module_param(refreshrate, uint, 0);
+
 static u_int contrast = 128;
 module_param(contrast, uint, S_IRUGO);
 
@@ -269,11 +274,6 @@ static void ssd1307fb_deferred_io(struct fb_info *info,
 	ssd1307fb_update_display(info->par);
 }
 
-static struct fb_deferred_io ssd1307fb_defio = {
-	.delay		= HZ,
-	.deferred_io	= ssd1307fb_deferred_io,
-};
-
 static int ssd1307fb_init(struct ssd1307fb_par *par)
 {
 	int ret;
@@ -474,6 +474,7 @@ static int ssd1307fb_probe(struct i2c_client *client,
 {
 	struct fb_info *info;
 	struct device_node *node = client->dev.of_node;
+	struct fb_deferred_io *ssd1307fb_defio;
 	u32 vmem_size;
 	struct ssd1307fb_par *par;
 	u8 *vmem;
@@ -544,10 +545,20 @@ static int ssd1307fb_probe(struct i2c_client *client,
 		goto fb_alloc_error;
 	}
 
+	ssd1307fb_defio = devm_kzalloc(&client->dev, sizeof(struct fb_deferred_io), GFP_KERNEL);
+	if (!ssd1307fb_defio) {
+		dev_err(&client->dev, "Couldn't allocate deferred io.\n");
+		ret = -ENOMEM;
+		goto fb_alloc_error;
+	}
+
+	ssd1307fb_defio->delay = HZ / refreshrate;
+	ssd1307fb_defio->deferred_io = ssd1307fb_deferred_io;
+
 	info->fbops = &ssd1307fb_ops;
 	info->fix = ssd1307fb_fix;
 	info->fix.line_length = par->width / 8;
-	info->fbdefio = &ssd1307fb_defio;
+	info->fbdefio = ssd1307fb_defio;
 
 	info->var = ssd1307fb_var;
 	info->var.xres = par->width;
-- 
2.3.0

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