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Commit 4c12adad authored by David Howells's avatar David Howells Committed by Mauro Carvalho Chehab
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[media] dvb: Document FE_SCALE_DECIBEL units consistently 



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: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent 24d795d3

Documentation/DocBook/media/dvb/dvbproperty.xml

+2 −2
Original line number Diff line number Diff line
@@ -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>

include/uapi/linux/dvb/frontend.h

+2 −2
Original line number Diff line number Diff line
@@ -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));