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[media] dvb: Document FE_SCALE_DECIBEL units consistently

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In comments and in the documentation, the units of properties marked
with the FE_SCALE_DECIBEL scale are specified in terms of 1/1000 dB
or 0.0001 dB.  This is inconsistent, however, as 1/1000 is 0.001,
not 0.0001.

Note that the v4l-utils divide the value by 1000 for the signal
strength suggesting that the 1/1000 is correct.

Settle on millidecibels, ie. 1/1000dB or 0.001dB.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
David Howells 2015-04-09 16:36:49 -03:00 committed by Mauro Carvalho Chehab
parent 24d795d361
commit 4c12adad26
2 changed files with 4 additions and 4 deletions
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4
Documentation/DocBook/media/dvb/dvbproperty.xml
View File

@ -953,7 +953,7 @@ enum fe_interleaving {
<para>Possible scales for this metric are:</para>
<itemizedlist mark='bullet'>
<listitem><para><constant>FE_SCALE_NOT_AVAILABLE</constant> - it failed to measure it, or the measurement was not complete yet.</para></listitem>
<listitem><para><constant>FE_SCALE_DECIBEL</constant> - signal strength is in 0.0001 dBm units, power measured in miliwatts. This value is generally negative.</para></listitem>
<listitem><para><constant>FE_SCALE_DECIBEL</constant> - signal strength is in 0.001 dBm units, power measured in miliwatts. This value is generally negative.</para></listitem>
<listitem><para><constant>FE_SCALE_RELATIVE</constant> - The frontend provides a 0% to 100% measurement for power (actually, 0 to 65535).</para></listitem>
</itemizedlist>
</section>
@ -963,7 +963,7 @@ enum fe_interleaving {
<para>Possible scales for this metric are:</para>
<itemizedlist mark='bullet'>
<listitem><para><constant>FE_SCALE_NOT_AVAILABLE</constant> - it failed to measure it, or the measurement was not complete yet.</para></listitem>
<listitem><para><constant>FE_SCALE_DECIBEL</constant> - Signal/Noise ratio is in 0.0001 dB units.</para></listitem>
<listitem><para><constant>FE_SCALE_DECIBEL</constant> - Signal/Noise ratio is in 0.001 dB units.</para></listitem>
<listitem><para><constant>FE_SCALE_RELATIVE</constant> - The frontend provides a 0% to 100% measurement for Signal/Noise (actually, 0 to 65535).</para></listitem>
</itemizedlist>
</section>

4
include/uapi/linux/dvb/frontend.h
View File

@ -467,7 +467,7 @@ struct dtv_cmds_h {
* @FE_SCALE_NOT_AVAILABLE: That QoS measure is not available. That
* could indicate a temporary or a permanent
* condition.
* @FE_SCALE_DECIBEL: The scale is measured in 0.0001 dB steps, typically
* @FE_SCALE_DECIBEL: The scale is measured in 0.001 dB steps, typically
* used on signal measures.
* @FE_SCALE_RELATIVE: The scale is a relative percentual measure,
* ranging from 0 (0%) to 0xffff (100%).
@ -516,7 +516,7 @@ struct dtv_stats {
__u8 scale; /* enum fecap_scale_params type */
union {
__u64 uvalue; /* for counters and relative scales */
__s64 svalue; /* for 0.0001 dB measures */
__s64 svalue; /* for 0.001 dB measures */
};
} __attribute__ ((packed));