<p>Harald Welte <strong>merged</strong> this change.</p><p><a href="https://gerrit.osmocom.org/12287">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Harald Welte: Looks good to me, approved
Jenkins Builder: Verified
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">osmo-bts-trx/loops.c: Add comments documenting TA + MS power control loop<br><br>The loops.c code is not very easily understood, so let's add some<br>comments to it.<br><br>As can be seen, there are functions of integer type which always return<br>0, and whose callers don't check for the return value. This will be<br>adressed in subsequent patches.<br><br>Change-Id: Iafea07eb751ed85d29b214576bb0d31ea919cd72<br>Related: OS#1622, OS#1851<br>---<br>M src/osmo-bts-trx/loops.c<br>1 file changed, 30 insertions(+), 0 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/src/osmo-bts-trx/loops.c b/src/osmo-bts-trx/loops.c</span><br><span>index 926b4c6..fc10c40 100644</span><br><span>--- a/src/osmo-bts-trx/loops.c</span><br><span>+++ b/src/osmo-bts-trx/loops.c</span><br><span>@@ -37,6 +37,11 @@</span><br><span> * MS Power loop</span><br><span> */</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! compute the new MS POWER LEVEL communicated to the MS and store it in lchan.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param lchan logical channel for which to compute (and in which to store) new power value.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param[in] chan_nr RSL channel number of the channel, only used for logging purpose.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param[in] diff input delta value (in dB)</span><br><span style="color: hsl(120, 100%, 40%);">+ * \returns 0 in all cases */</span><br><span> static int ms_power_diff(struct gsm_lchan *lchan, uint8_t chan_nr, int8_t diff)</span><br><span> {</span><br><span> struct gsm_bts_trx *trx = lchan->ts->trx;</span><br><span>@@ -44,14 +49,17 @@</span><br><span> uint16_t arfcn = trx->arfcn;</span><br><span> int8_t new_power;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* compute new target MS output power level based on current value subtracted by 'diff/2' */</span><br><span> new_power = lchan->ms_power_ctrl.current - (diff >> 1);</span><br><span> </span><br><span> if (diff == 0)</span><br><span> return 0;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* ms transmit power level cannot become negative */</span><br><span> if (new_power < 0)</span><br><span> new_power = 0;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* saturate at the maximum possible power level for the given band */</span><br><span> // FIXME: to go above 1W, we need to know classmark of MS</span><br><span> if (arfcn >= 512 && arfcn <= 885) {</span><br><span> if (new_power > 15)</span><br><span>@@ -61,6 +69,8 @@</span><br><span> new_power = 19;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* don't ever change more than MS_{LOWER,RAISE}_MAX during one loop iteration, i.e.</span><br><span style="color: hsl(120, 100%, 40%);">+ * reduce the speed at which the MS transmit power can change */</span><br><span> /* a higher value means a lower level (and vice versa) */</span><br><span> if (new_power > lchan->ms_power_ctrl.current + MS_LOWER_MAX)</span><br><span> new_power = lchan->ms_power_ctrl.current + MS_LOWER_MAX;</span><br><span>@@ -83,11 +93,16 @@</span><br><span> ms_pwr_dbm(band, lchan->ms_power_ctrl.current), new_power,</span><br><span> ms_pwr_dbm(band, new_power));</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* store the resulting new MS power level in the lchan */</span><br><span> lchan->ms_power_ctrl.current = new_power;</span><br><span> </span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! Input a new RSSI value into the MS power control loop for the given logical channel.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param chan_state L1 channel state of the logical channel.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param rssi Received Signal Strength Indication (in dBm)</span><br><span style="color: hsl(120, 100%, 40%);">+ * \return 0 in all cases */</span><br><span> static int ms_power_val(struct l1sched_chan_state *chan_state, int8_t rssi)</span><br><span> {</span><br><span> /* ignore inserted dummy frames, treat as lost frames */</span><br><span>@@ -110,6 +125,10 @@</span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! Process a single clock tick of the MS power control loop.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param lchan Logical channel to which the clock tick applies</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param[in] chan_nr RSL channel number (for logging purpose)</span><br><span style="color: hsl(120, 100%, 40%);">+ * \returns 0 in all cases */</span><br><span> static int ms_power_clock(struct gsm_lchan *lchan,</span><br><span> uint8_t chan_nr, struct l1sched_chan_state *chan_state)</span><br><span> {</span><br><span>@@ -213,6 +232,14 @@</span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! Process a SACCH event as input to the MS power control and TA loop. Function</span><br><span style="color: hsl(120, 100%, 40%);">+ * is called once every uplink SACCH block is received.</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param l1t L1 TRX instance on which we operate</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param chan_nr RSL channel number on which we operate</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param chan_state L1 scheduler channel state of the channel on which we operate</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param[in] rssi Receive Signal Strength Indication</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param[in] toa256 Time of Arrival in 1/256 symbol periods</span><br><span style="color: hsl(120, 100%, 40%);">+ * \returns 0 in all cases */</span><br><span> int trx_loop_sacch_input(struct l1sched_trx *l1t, uint8_t chan_nr,</span><br><span> struct l1sched_chan_state *chan_state, int8_t rssi, int16_t toa256)</span><br><span> {</span><br><span>@@ -220,15 +247,18 @@</span><br><span> .lchan[l1sap_chan2ss(chan_nr)];</span><br><span> struct phy_instance *pinst = trx_phy_instance(l1t->trx);</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* if MS power control loop is enabled, handle it */</span><br><span> if (pinst->phy_link->u.osmotrx.trx_ms_power_loop)</span><br><span> ms_power_val(chan_state, rssi);</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* if TA loop is enabled, handle it */</span><br><span> if (pinst->phy_link->u.osmotrx.trx_ta_loop)</span><br><span> ta_val(lchan, chan_nr, chan_state, toa256);</span><br><span> </span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! Called once every downlink SACCH block needs to be sent. */</span><br><span> int trx_loop_sacch_clock(struct l1sched_trx *l1t, uint8_t chan_nr,</span><br><span> struct l1sched_chan_state *chan_state)</span><br><span> {</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/12287">change 12287</a>. To unsubscribe, or for help writing mail filters, visit <a href="https://gerrit.osmocom.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.osmocom.org/12287"/><meta itemprop="name" content="View Change"/></div></div>
<div style="display:none"> Gerrit-Project: osmo-bts </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-MessageType: merged </div>
<div style="display:none"> Gerrit-Change-Id: Iafea07eb751ed85d29b214576bb0d31ea919cd72 </div>
<div style="display:none"> Gerrit-Change-Number: 12287 </div>
<div style="display:none"> Gerrit-PatchSet: 3 </div>
<div style="display:none"> Gerrit-Owner: Harald Welte <laforge@gnumonks.org> </div>
<div style="display:none"> Gerrit-Reviewer: Harald Welte <laforge@gnumonks.org> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder (1000002) </div>
<div style="display:none"> Gerrit-Reviewer: Pau Espin Pedrol <pespin@sysmocom.de> </div>