V4L/DVB (13442): ivtv: Add module parameter to adjust I2C SCL clock period per board

Add a module parameter to adjust I2C SCL clock period per board.  This allows
some experimental fine tuning by end users to overcome quirky I2C device
problems.

Reported-by: "Aleksandr V. Piskunov" <aleksandr.v.piskunov@gmail.com>
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 28 insertions, 2 deletions

diff --git a/drivers/media/video/ivtv/ivtv-driver.c b/drivers/media/video/ivtv/ivtv-driver.c
index 7cdbc1a8f218..8330fb5c7eb3 100644
--- a/drivers/media/video/ivtv/ivtv-driver.c
+++ b/drivers/media/video/ivtv/ivtv-driver.c
@@ -91,10 +91,15 @@ static int radio[IVTV_MAX_CARDS] = { -1, -1, -1, -1, -1, -1, -1, -1,
                                      -1, -1, -1, -1, -1, -1, -1, -1,
                                      -1, -1, -1, -1, -1, -1, -1, -1,
                                      -1, -1, -1, -1, -1, -1, -1, -1 };
+static int i2c_clock_period[IVTV_MAX_CARDS] = { -1, -1, -1, -1, -1, -1, -1, -1,
+                                               -1, -1, -1, -1, -1, -1, -1, -1,
+                                               -1, -1, -1, -1, -1, -1, -1, -1,
+                                               -1, -1, -1, -1, -1, -1, -1, -1 };
 
 static unsigned int cardtype_c = 1;
 static unsigned int tuner_c = 1;
 static unsigned int radio_c = 1;
+static unsigned int i2c_clock_period_c = 1;
 static char pal[] = "---";
 static char secam[] = "--";
 static char ntsc[] = "-";
@@ -151,6 +156,7 @@ module_param(dec_vbi_buffers, int, 0644);
 
 module_param(tunertype, int, 0644);
 module_param(newi2c, int, 0644);
+module_param_array(i2c_clock_period, int, &i2c_clock_period_c, 0644);
 
 MODULE_PARM_DESC(tuner, "Tuner type selection,\n"
                         "\t\t\tsee tuner.h for values");
@@ -245,6 +251,10 @@ MODULE_PARM_DESC(newi2c,
                  "Use new I2C implementation\n"
                  "\t\t\t-1 is autodetect, 0 is off, 1 is on\n"
                  "\t\t\tDefault is autodetect");
+MODULE_PARM_DESC(i2c_clock_period,
+                 "Period of SCL for the I2C bus controlled by the CX23415/6\n"
+                 "\t\t\tMin: 10 usec (100 kHz), Max: 4500 usec (222 Hz)\n"
+                 "\t\t\tDefault: " __stringify(IVTV_DEFAULT_I2C_CLOCK_PERIOD));
 
 MODULE_PARM_DESC(ivtv_first_minor, "Set device node number assigned to first card");
 
@@ -600,6 +610,15 @@ static void ivtv_process_options(struct ivtv *itv)
         itv->options.cardtype = cardtype[itv->instance];
         itv->options.tuner = tuner[itv->instance];
         itv->options.radio = radio[itv->instance];
+
+        itv->options.i2c_clock_period = i2c_clock_period[itv->instance];
+        if (itv->options.i2c_clock_period == -1)
+                itv->options.i2c_clock_period = IVTV_DEFAULT_I2C_CLOCK_PERIOD;
+        else if (itv->options.i2c_clock_period < 10)
+                itv->options.i2c_clock_period = 10;
+        else if (itv->options.i2c_clock_period > 4500)
+                itv->options.i2c_clock_period = 4500;
+
         itv->options.newi2c = newi2c;
         if (tunertype < -1 || tunertype > 1) {
                 IVTV_WARN("Invalid tunertype argument, will autodetect instead\n");
diff --git a/drivers/media/video/ivtv/ivtv-driver.h b/drivers/media/video/ivtv/ivtv-driver.h
index 440f7328a7ed..2b3db90afb74 100644
--- a/drivers/media/video/ivtv/ivtv-driver.h
+++ b/drivers/media/video/ivtv/ivtv-driver.h
@@ -176,12 +176,16 @@ extern int ivtv_debug;
 
 #define IVTV_MAX_PGM_INDEX (400)
 
+/* Default I2C SCL period in microseconds */
+#define IVTV_DEFAULT_I2C_CLOCK_PERIOD   20
+
 struct ivtv_options {
         int kilobytes[IVTV_MAX_STREAMS];        /* size in kilobytes of each stream */
         int cardtype;                           /* force card type on load */
         int tuner;                              /* set tuner on load */
         int radio;                              /* enable/disable radio */
         int newi2c;                             /* new I2C algorithm */
+        int i2c_clock_period;                   /* period of SCL for I2C bus */
 };
 
 /* ivtv-specific mailbox template */
diff --git a/drivers/media/video/ivtv/ivtv-i2c.c b/drivers/media/video/ivtv/ivtv-i2c.c
index b9c71e61f7d6..d4cc3365038e 100644
--- a/drivers/media/video/ivtv/ivtv-i2c.c
+++ b/drivers/media/video/ivtv/ivtv-i2c.c
@@ -564,13 +564,15 @@ static struct i2c_adapter ivtv_i2c_adap_template = {
         .owner = THIS_MODULE,
 };
 
+#define IVTV_ALGO_BIT_TIMEOUT   (2)     /* seconds */
+
 static const struct i2c_algo_bit_data ivtv_i2c_algo_template = {
         .setsda         = ivtv_setsda_old,
         .setscl         = ivtv_setscl_old,
         .getsda         = ivtv_getsda_old,
         .getscl         = ivtv_getscl_old,
-        .udelay         = 10,
-        .timeout        = 200,
+        .udelay         = IVTV_DEFAULT_I2C_CLOCK_PERIOD / 2,  /* microseconds */
+        .timeout        = IVTV_ALGO_BIT_TIMEOUT * HZ,         /* jiffies */
 };
 
 static struct i2c_client ivtv_i2c_client_template = {
@@ -602,6 +604,7 @@ int init_ivtv_i2c(struct ivtv *itv)
                 memcpy(&itv->i2c_algo, &ivtv_i2c_algo_template,
                        sizeof(struct i2c_algo_bit_data));
         }
+        itv->i2c_algo.udelay = itv->options.i2c_clock_period / 2;
         itv->i2c_algo.data = itv;
         itv->i2c_adap.algo_data = &itv->i2c_algo;