The DVBv3 quality parameters are limited on several ways:
- Doesn't provide any way to indicate the used measure;
- Userspace need to guess how to calculate the measure;
- Only a limited set of stats are supported;
- Doesn't provide QoS measure for the OFDM TPS/TMCC
carriers, used to detect the network parameters for
DVB-T/ISDB-T;
- Can't be called in a way to require them to be filled
all at once (atomic reads from the hardware), with may
cause troubles on interpreting them on userspace;
- On some OFDM delivery systems, the carriers can be
independently modulated, having different properties.
Currently, there's no way to report per-layer stats;
This RFC adds the header definitions meant to solve that issues.
After discussed, I'll write a patch for the DocBook and add support
for it on some demods. Support for dvbv5-zap and dvbv5-scan tools
will also have support for those features.
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
---
include/linux/dvb/frontend.h | 78 +++++++++++++++++++++++++++++++++++++++++-
1 files changed, 77 insertions(+), 1 deletions(-)
diff --git a/include/linux/dvb/frontend.h b/include/linux/dvb/frontend.h
index cb4428a..f9cdb7d 100644
--- a/include/linux/dvb/frontend.h
+++ b/include/linux/dvb/frontend.h
@@ -320,7 +320,21 @@ struct dvb_frontend_event {
#define DTV_ENUM_DELSYS 44
-#define DTV_MAX_COMMAND DTV_ENUM_DELSYS
+/* Quality parameters */
+#define DTV_ENUM_QUALITY 45 /* Enumerates supported QoS parameters */
+#define DTV_QUALITY_SNR 46
+#define DTV_QUALITY_CNR 47
+#define DTV_QUALITY_EsNo 48
+#define DTV_QUALITY_EbNo 49
+#define DTV_QUALITY_RELATIVE 50
+#define DTV_ERROR_BER 51
+#define DTV_ERROR_PER 52
+#define DTV_ERROR_PARAMS 53 /* Error count at TMCC or TPS carrier */
+#define DTV_FE_STRENGTH 54
+#define DTV_FE_SIGNAL 55
+#define DTV_FE_UNC 56
+
+#define DTV_MAX_COMMAND DTV_FE_UNC
typedef enum fe_pilot {
PILOT_ON,
@@ -372,12 +386,74 @@ struct dtv_cmds_h {
__u32 reserved:30; /* Align */
};
+/**
+ * Scale types for the quality parameters.
+ * @FE_SCALE_DECIBEL: The scale is measured in dB, typically
+ * used on signal measures.
+ * @FE_SCALE_LINEAR: The scale is linear.
+ * typically used on error QoS parameters.
+ * @FE_SCALE_RELATIVE: The scale is relative.
+ */
+enum fecap_scale_params {
+ FE_SCALE_DECIBEL,
+ FE_SCALE_LINEAR,
+ FE_SCALE_RELATIVE
+};
+
+/**
+ * struct dtv_status - Used for reading a DTV status property
+ *
+ * @value: value of the measure. Should range from 0 to 0xffff;
+ * @scale: Filled with enum fecap_scale_params - the scale
+ * in usage for that parameter
+ * @min: minimum value. Not used if the scale is relative.
+ * For non-relative measures, define the measure
+ * associated with dtv_status.value == 0.
+ * @max: maximum value. Not used if the scale is relative.
+ * For non-relative measures, define the measure
+ * associated with dtv_status.value == 0xffff.
+ *
+ * At userspace, min/max values should be used to calculate the
+ * absolute value of that measure, if fecap_scale_params is not
+ * FE_SCALE_RELATIVE, using the following formula:
+ * measure = min + (value * (max - min) / 0xffff)
+ *
+ * For error count measures, typically, min = 0, and max = 0xffff,
+ * and the measure represent the number of errors detected.
+ *
+ * Up to 4 status groups can be provided. This is for the
+ * OFDM standards where the carriers can be grouped into
+ * independent layers, each with its own modulation. When
+ * such layers are used (for example, on ISDB-T), the status
+ * should be filled with:
+ * stat.status[0] = global statistics;
+ * stat.status[1] = layer A statistics;
+ * stat.status[2] = layer B statistics;
+ * stat.status[3] = layer C statistics.
+ * and stat.len should be filled with the latest filled status + 1.
+ * If the frontend doesn't provide a global statistics,
+ * stat.has_global should be 0.
+ * Delivery systems that don't use it, should just set stat.len and
+ * stat.has_global with 1, and fill just stat.status[0].
+ */
+struct dtv_status {
+ __u16 value;
+ __u16 scale;
+ __s16 min;
+ __s16 max;
+} __attribute__ ((packed));
+
struct dtv_property {
__u32 cmd;
__u32 reserved[3];
union {
__u32 data;
struct {
+ __u8 len;
+ __u8 has_global;
+ struct dtv_status status[4];
+ } stat;
+ struct {
__u8 data[32];
__u32 len;
__u32 reserved1[3];
--
1.7.8
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