[media] r820t: Allow disabling IMR callibration

The rtl-sdr library disabled IMR callibration. While I'm not sure
yet why, it could be a good idea to add a modprobe parameter here,
to allow to also disable it. There are two rationale behind it:
- It helps to compare USB dumps between rtl-sdr and the Kernel module;
- If rtl-sdr disabled it, perhaps there's a good reason (e. g. it
  might not be actually working, or it might be causing some trouble).
For both cases, it seems useful to add a modprobe parameter to allow
testing the device with both configurations.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: Antti Palosaari <crope@iki.fi>

1 files changed, 19 insertions, 4 deletions

diff --git a/drivers/media/tuners/r820t.c b/drivers/media/tuners/r820t.c
index 0125de897c8d..2e6a690ffb1a 100644
--- a/drivers/media/tuners/r820t.c
+++ b/drivers/media/tuners/r820t.c
@@ -56,6 +56,11 @@ static int debug;
 module_param(debug, int, 0644);
 MODULE_PARM_DESC(debug, "enable verbose debug messages");
 
+static int no_imr_cal;
+module_param(no_imr_cal, int, 0444);
+MODULE_PARM_DESC(no_imr_cal, "Disable IMR calibration at module init");
+
+
 /*
  * enums and structures
  */
@@ -87,7 +92,8 @@ struct r820t_priv {
         u32                             int_freq;
         u8                              fil_cal_code;
         bool                            imr_done;
-
+        bool                            has_lock;
+        bool                            init_done;
         struct r820t_sect_type          imr_data[NUM_IMR];
 
         /* Store current mode */
@@ -95,8 +101,6 @@ struct r820t_priv {
         enum v4l2_tuner_type            type;
         v4l2_std_id                     std;
         u32                             bw;     /* in MHz */
-
-        bool                            has_lock;
 };
 
 struct r820t_freq_range {
@@ -1999,7 +2003,7 @@ static int r820t_imr_callibrate(struct r820t_priv *priv)
         int rc, i;
         int xtal_cap = 0;
 
-        if (priv->imr_done)
+        if (priv->init_done)
                 return 0;
 
         /* Initialize registers */
@@ -2024,6 +2028,16 @@ static int r820t_imr_callibrate(struct r820t_priv *priv)
                 priv->xtal_cap_sel = xtal_cap;
         }
 
+        /*
+         * Disables IMR callibration. That emulates the same behaviour
+         * as what is done by rtl-sdr userspace library. Useful for testing
+         */
+        if (no_imr_cal) {
+                priv->init_done = true;
+
+                return 0;
+        }
+
         /* Initialize registers */
         rc = r820t_write(priv, 0x05,
                          r820t_init_array, sizeof(r820t_init_array));
@@ -2050,6 +2064,7 @@ static int r820t_imr_callibrate(struct r820t_priv *priv)
         if (rc < 0)
                 return rc;
 
+        priv->init_done = true;
         priv->imr_done = true;
 
         return 0;