Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757966AbaKTTmO (ORCPT ); Thu, 20 Nov 2014 14:42:14 -0500 Received: from mail-qg0-f41.google.com ([209.85.192.41]:35044 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755849AbaKTTmN (ORCPT ); Thu, 20 Nov 2014 14:42:13 -0500 MIME-Version: 1.0 In-Reply-To: <20141031165136.GB32331@dtor-ws> References: <1414693987-6059-1-git-send-email-benjamin.tissoires@redhat.com> <20141031165136.GB32331@dtor-ws> Date: Thu, 20 Nov 2014 14:42:11 -0500 Message-ID: Subject: Re: [PATCH 1/2] Input: synaptics: Use in-kernel tracking for reporting mt data From: Benjamin Tissoires To: Dmitry Torokhov Cc: Benjamin Tissoires , Henrik Rydberg , Hans de Goede , Peter Hutterer , linux-input , "linux-kernel@vger.kernel.org" , Daniel Kurtz , Chung-yih Wang Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 31, 2014 at 12:51 PM, Dmitry Torokhov wrote: > On Thu, Oct 30, 2014 at 02:33:06PM -0400, Benjamin Tissoires wrote: >> The current code tries to consider all states and transitions to properly >> detect which finger is attached to which slot. The code is quite huge >> and difficult to read. >> If the sensor manages to group the touch points but is not reliable in >> giving tracking ids, we can simply use the kernel tracking method. Note >> that it is already used by Cr-48 Chromebooks. >> >> Incidentaly, this fixes a bug reported by Peter Hutterer: >> """ >> on the Lenovo T440, run: >> evemu-record /dev/input/event4 | grep BTN_ >> >> then put one, two, three, two fingers down >> when you go from 3 to 2 fingers the driver sends a spurious BTN_TOUCH 0 >> event: >> >> E: 0.000000 0001 014a 0001 # EV_KEY / BTN_TOUCH 1 >> E: 0.000000 0001 0145 0001 # EV_KEY / BTN_TOOL_FINGER 1 >> E: 0.770008 0001 0145 0000 # EV_KEY / BTN_TOOL_FINGER 0 >> E: 0.770008 0001 014d 0001 # EV_KEY / BTN_TOOL_DOUBLETAP 1 >> E: 1.924716 0001 014d 0000 # EV_KEY / BTN_TOOL_DOUBLETAP 0 >> E: 1.924716 0001 014e 0001 # EV_KEY / BTN_TOOL_TRIPLETAP 1 >> >> .. changing from 3 to 2 fingers now >> >> E: 3.152641 0001 014a 0000 # EV_KEY / BTN_TOUCH 0 >> E: 3.152641 0001 014d 0001 # EV_KEY / BTN_TOOL_DOUBLETAP 1 >> E: 3.152641 0001 014e 0000 # EV_KEY / BTN_TOOL_TRIPLETAP 0 >> E: 3.176948 0001 014a 0001 # EV_KEY / BTN_TOUCH 1 >> >> quick look in the kernel shows it's caused by hw.z going to 0 for a packet, >> so probably a firmware bug. either way, it makes it hard to track BTN_TOUCH >> as signal that at least one finger is down. >> """ >> >> The in-kernel tracking is enough to remove this spurious BTN_TOUCH 0. >> >> Signed-off-by: Benjamin Tissoires >> --- >> >> Hi Dmitry, >> >> I started working on that for 2 other bug reports >> https://bugs.freedesktop.org/show_bug.cgi?id=81278 >> and >> https://bugs.freedesktop.org/show_bug.cgi?id=76722 >> >> I thought the cursor jumps could be fixed by the in-kernel tracking, but the >> tracking needs a little bit more work to filter them out (patches to follow soon). >> >> From a user perspective, this patch does not change anything to what the user >> previously had. It also fixes Peter's bug that's why I decide to send this out >> by itself (removing ~350 lines of code and fixing bugs is always nice). >> >> I think the cursor jump fixes will need more bikeshedding in input-mt.c (I am >> *really* bad at designing APIs), so I'll send it later as an RFC. > > Daniel and Chung-yih were working on the driver so let's see if they > have a moment... > Any news from the chrome team? This is a requirement for fixing the cursor jumps, and I'd rather have this series in shape before introducing the changes in input-mt.c. Cheers, Benjamin >> >> Cheers, >> Benjamin >> >> drivers/input/mouse/synaptics.c | 397 ++++------------------------------------ >> drivers/input/mouse/synaptics.h | 18 +- >> 2 files changed, 34 insertions(+), 381 deletions(-) >> >> diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c >> index 9031a0a..fd89249 100644 >> --- a/drivers/input/mouse/synaptics.c >> +++ b/drivers/input/mouse/synaptics.c >> @@ -569,14 +569,6 @@ static void synaptics_pt_create(struct psmouse *psmouse) >> * Functions to interpret the absolute mode packets >> ****************************************************************************/ >> >> -static void synaptics_mt_state_set(struct synaptics_mt_state *state, int count, >> - int sgm, int agm) >> -{ >> - state->count = count; >> - state->sgm = sgm; >> - state->agm = agm; >> -} >> - >> static void synaptics_parse_agm(const unsigned char buf[], >> struct synaptics_data *priv, >> struct synaptics_hw_state *hw) >> @@ -595,16 +587,13 @@ static void synaptics_parse_agm(const unsigned char buf[], >> break; >> >> case 2: >> - /* AGM-CONTACT packet: (count, sgm, agm) */ >> - synaptics_mt_state_set(&agm->mt_state, buf[1], buf[2], buf[4]); >> + /* AGM-CONTACT packet: we are only interested in the count */ >> + priv->agm_count = buf[1]; >> break; >> >> default: >> break; >> } >> - >> - /* Record that at least one AGM has been received since last SGM */ >> - priv->agm_pending = true; >> } >> >> static bool is_forcepad; >> @@ -798,388 +787,68 @@ static void synaptics_report_buttons(struct psmouse *psmouse, >> input_report_key(dev, BTN_0 + i, hw->ext_buttons & (1 << i)); >> } >> >> -static void synaptics_report_slot(struct input_dev *dev, int slot, >> - const struct synaptics_hw_state *hw) >> -{ >> - input_mt_slot(dev, slot); >> - input_mt_report_slot_state(dev, MT_TOOL_FINGER, (hw != NULL)); >> - if (!hw) >> - return; >> - >> - input_report_abs(dev, ABS_MT_POSITION_X, hw->x); >> - input_report_abs(dev, ABS_MT_POSITION_Y, synaptics_invert_y(hw->y)); >> - input_report_abs(dev, ABS_MT_PRESSURE, hw->z); >> -} >> - >> static void synaptics_report_mt_data(struct psmouse *psmouse, >> - struct synaptics_mt_state *mt_state, >> - const struct synaptics_hw_state *sgm) >> + const struct synaptics_hw_state *sgm, >> + int num_fingers) >> { >> struct input_dev *dev = psmouse->dev; >> struct synaptics_data *priv = psmouse->private; >> - struct synaptics_hw_state *agm = &priv->agm; >> - struct synaptics_mt_state *old = &priv->mt_state; >> + const struct synaptics_hw_state *hw[2] = { sgm, &priv->agm }; >> + struct input_mt_pos pos[2]; >> + int slot[2], nsemi, i; >> >> - switch (mt_state->count) { >> - case 0: >> - synaptics_report_slot(dev, 0, NULL); >> - synaptics_report_slot(dev, 1, NULL); >> - break; >> - case 1: >> - if (mt_state->sgm == -1) { >> - synaptics_report_slot(dev, 0, NULL); >> - synaptics_report_slot(dev, 1, NULL); >> - } else if (mt_state->sgm == 0) { >> - synaptics_report_slot(dev, 0, sgm); >> - synaptics_report_slot(dev, 1, NULL); >> - } else { >> - synaptics_report_slot(dev, 0, NULL); >> - synaptics_report_slot(dev, 1, sgm); >> - } >> - break; >> - default: >> - /* >> - * If the finger slot contained in SGM is valid, and either >> - * hasn't changed, or is new, or the old SGM has now moved to >> - * AGM, then report SGM in MTB slot 0. >> - * Otherwise, empty MTB slot 0. >> - */ >> - if (mt_state->sgm != -1 && >> - (mt_state->sgm == old->sgm || >> - old->sgm == -1 || mt_state->agm == old->sgm)) >> - synaptics_report_slot(dev, 0, sgm); >> - else >> - synaptics_report_slot(dev, 0, NULL); >> + nsemi = clamp_val(num_fingers, 0, 2); >> >> - /* >> - * If the finger slot contained in AGM is valid, and either >> - * hasn't changed, or is new, then report AGM in MTB slot 1. >> - * Otherwise, empty MTB slot 1. >> - * >> - * However, in the case where the AGM is new, make sure that >> - * that it is either the same as the old SGM, or there was no >> - * SGM. >> - * >> - * Otherwise, if the SGM was just 1, and the new AGM is 2, then >> - * the new AGM will keep the old SGM's tracking ID, which can >> - * cause apparent drumroll. This happens if in the following >> - * valid finger sequence: >> - * >> - * Action SGM AGM (MTB slot:Contact) >> - * 1. Touch contact 0 (0:0) >> - * 2. Touch contact 1 (0:0, 1:1) >> - * 3. Lift contact 0 (1:1) >> - * 4. Touch contacts 2,3 (0:2, 1:3) >> - * >> - * In step 4, contact 3, in AGM must not be given the same >> - * tracking ID as contact 1 had in step 3. To avoid this, >> - * the first agm with contact 3 is dropped and slot 1 is >> - * invalidated (tracking ID = -1). >> - */ >> - if (mt_state->agm != -1 && >> - (mt_state->agm == old->agm || >> - (old->agm == -1 && >> - (old->sgm == -1 || mt_state->agm == old->sgm)))) >> - synaptics_report_slot(dev, 1, agm); >> - else >> - synaptics_report_slot(dev, 1, NULL); >> - break; >> + for (i = 0; i < nsemi; i++) { >> + pos[i].x = hw[i]->x; >> + pos[i].y = synaptics_invert_y(hw[i]->y); >> } >> >> + input_mt_assign_slots(dev, slot, pos, nsemi); >> + >> + for (i = 0; i < nsemi; i++) { >> + input_mt_slot(dev, slot[i]); >> + input_mt_report_slot_state(dev, MT_TOOL_FINGER, true); >> + input_report_abs(dev, ABS_MT_POSITION_X, pos[i].x); >> + input_report_abs(dev, ABS_MT_POSITION_Y, pos[i].y); >> + input_report_abs(dev, ABS_MT_PRESSURE, hw[i]->z); >> + } >> + >> + input_mt_drop_unused(dev); >> + >> /* Don't use active slot count to generate BTN_TOOL events. */ >> input_mt_report_pointer_emulation(dev, false); >> >> /* Send the number of fingers reported by touchpad itself. */ >> - input_mt_report_finger_count(dev, mt_state->count); >> + input_mt_report_finger_count(dev, num_fingers); >> >> synaptics_report_buttons(psmouse, sgm); >> >> input_sync(dev); >> } >> >> -/* Handle case where mt_state->count = 0 */ >> -static void synaptics_image_sensor_0f(struct synaptics_data *priv, >> - struct synaptics_mt_state *mt_state) >> -{ >> - synaptics_mt_state_set(mt_state, 0, -1, -1); >> - priv->mt_state_lost = false; >> -} >> - >> -/* Handle case where mt_state->count = 1 */ >> -static void synaptics_image_sensor_1f(struct synaptics_data *priv, >> - struct synaptics_mt_state *mt_state) >> -{ >> - struct synaptics_hw_state *agm = &priv->agm; >> - struct synaptics_mt_state *old = &priv->mt_state; >> - >> - /* >> - * If the last AGM was (0,0,0), and there is only one finger left, >> - * then we absolutely know that SGM contains slot 0, and all other >> - * fingers have been removed. >> - */ >> - if (priv->agm_pending && agm->z == 0) { >> - synaptics_mt_state_set(mt_state, 1, 0, -1); >> - priv->mt_state_lost = false; >> - return; >> - } >> - >> - switch (old->count) { >> - case 0: >> - synaptics_mt_state_set(mt_state, 1, 0, -1); >> - break; >> - case 1: >> - /* >> - * If mt_state_lost, then the previous transition was 3->1, >> - * and SGM now contains either slot 0 or 1, but we don't know >> - * which. So, we just assume that the SGM now contains slot 1. >> - * >> - * If pending AGM and either: >> - * (a) the previous SGM slot contains slot 0, or >> - * (b) there was no SGM slot >> - * then, the SGM now contains slot 1 >> - * >> - * Case (a) happens with very rapid "drum roll" gestures, where >> - * slot 0 finger is lifted and a new slot 1 finger touches >> - * within one reporting interval. >> - * >> - * Case (b) happens if initially two or more fingers tap >> - * briefly, and all but one lift before the end of the first >> - * reporting interval. >> - * >> - * (In both these cases, slot 0 will becomes empty, so SGM >> - * contains slot 1 with the new finger) >> - * >> - * Else, if there was no previous SGM, it now contains slot 0. >> - * >> - * Otherwise, SGM still contains the same slot. >> - */ >> - if (priv->mt_state_lost || >> - (priv->agm_pending && old->sgm <= 0)) >> - synaptics_mt_state_set(mt_state, 1, 1, -1); >> - else if (old->sgm == -1) >> - synaptics_mt_state_set(mt_state, 1, 0, -1); >> - break; >> - case 2: >> - /* >> - * If mt_state_lost, we don't know which finger SGM contains. >> - * >> - * So, report 1 finger, but with both slots empty. >> - * We will use slot 1 on subsequent 1->1 >> - */ >> - if (priv->mt_state_lost) { >> - synaptics_mt_state_set(mt_state, 1, -1, -1); >> - break; >> - } >> - /* >> - * Since the last AGM was NOT (0,0,0), it was the finger in >> - * slot 0 that has been removed. >> - * So, SGM now contains previous AGM's slot, and AGM is now >> - * empty. >> - */ >> - synaptics_mt_state_set(mt_state, 1, old->agm, -1); >> - break; >> - case 3: >> - /* >> - * Since last AGM was not (0,0,0), we don't know which finger >> - * is left. >> - * >> - * So, report 1 finger, but with both slots empty. >> - * We will use slot 1 on subsequent 1->1 >> - */ >> - synaptics_mt_state_set(mt_state, 1, -1, -1); >> - priv->mt_state_lost = true; >> - break; >> - case 4: >> - case 5: >> - /* mt_state was updated by AGM-CONTACT packet */ >> - break; >> - } >> -} >> - >> -/* Handle case where mt_state->count = 2 */ >> -static void synaptics_image_sensor_2f(struct synaptics_data *priv, >> - struct synaptics_mt_state *mt_state) >> -{ >> - struct synaptics_mt_state *old = &priv->mt_state; >> - >> - switch (old->count) { >> - case 0: >> - synaptics_mt_state_set(mt_state, 2, 0, 1); >> - break; >> - case 1: >> - /* >> - * If previous SGM contained slot 1 or higher, SGM now contains >> - * slot 0 (the newly touching finger) and AGM contains SGM's >> - * previous slot. >> - * >> - * Otherwise, SGM still contains slot 0 and AGM now contains >> - * slot 1. >> - */ >> - if (old->sgm >= 1) >> - synaptics_mt_state_set(mt_state, 2, 0, old->sgm); >> - else >> - synaptics_mt_state_set(mt_state, 2, 0, 1); >> - break; >> - case 2: >> - /* >> - * If mt_state_lost, SGM now contains either finger 1 or 2, but >> - * we don't know which. >> - * So, we just assume that the SGM contains slot 0 and AGM 1. >> - */ >> - if (priv->mt_state_lost) >> - synaptics_mt_state_set(mt_state, 2, 0, 1); >> - /* >> - * Otherwise, use the same mt_state, since it either hasn't >> - * changed, or was updated by a recently received AGM-CONTACT >> - * packet. >> - */ >> - break; >> - case 3: >> - /* >> - * 3->2 transitions have two unsolvable problems: >> - * 1) no indication is given which finger was removed >> - * 2) no way to tell if agm packet was for finger 3 >> - * before 3->2, or finger 2 after 3->2. >> - * >> - * So, report 2 fingers, but empty all slots. >> - * We will guess slots [0,1] on subsequent 2->2. >> - */ >> - synaptics_mt_state_set(mt_state, 2, -1, -1); >> - priv->mt_state_lost = true; >> - break; >> - case 4: >> - case 5: >> - /* mt_state was updated by AGM-CONTACT packet */ >> - break; >> - } >> -} >> - >> -/* Handle case where mt_state->count = 3 */ >> -static void synaptics_image_sensor_3f(struct synaptics_data *priv, >> - struct synaptics_mt_state *mt_state) >> -{ >> - struct synaptics_mt_state *old = &priv->mt_state; >> - >> - switch (old->count) { >> - case 0: >> - synaptics_mt_state_set(mt_state, 3, 0, 2); >> - break; >> - case 1: >> - /* >> - * If previous SGM contained slot 2 or higher, SGM now contains >> - * slot 0 (one of the newly touching fingers) and AGM contains >> - * SGM's previous slot. >> - * >> - * Otherwise, SGM now contains slot 0 and AGM contains slot 2. >> - */ >> - if (old->sgm >= 2) >> - synaptics_mt_state_set(mt_state, 3, 0, old->sgm); >> - else >> - synaptics_mt_state_set(mt_state, 3, 0, 2); >> - break; >> - case 2: >> - /* >> - * If the AGM previously contained slot 3 or higher, then the >> - * newly touching finger is in the lowest available slot. >> - * >> - * If SGM was previously 1 or higher, then the new SGM is >> - * now slot 0 (with a new finger), otherwise, the new finger >> - * is now in a hidden slot between 0 and AGM's slot. >> - * >> - * In all such cases, the SGM now contains slot 0, and the AGM >> - * continues to contain the same slot as before. >> - */ >> - if (old->agm >= 3) { >> - synaptics_mt_state_set(mt_state, 3, 0, old->agm); >> - break; >> - } >> - >> - /* >> - * After some 3->1 and all 3->2 transitions, we lose track >> - * of which slot is reported by SGM and AGM. >> - * >> - * For 2->3 in this state, report 3 fingers, but empty all >> - * slots, and we will guess (0,2) on a subsequent 0->3. >> - * >> - * To userspace, the resulting transition will look like: >> - * 2:[0,1] -> 3:[-1,-1] -> 3:[0,2] >> - */ >> - if (priv->mt_state_lost) { >> - synaptics_mt_state_set(mt_state, 3, -1, -1); >> - break; >> - } >> - >> - /* >> - * If the (SGM,AGM) really previously contained slots (0, 1), >> - * then we cannot know what slot was just reported by the AGM, >> - * because the 2->3 transition can occur either before or after >> - * the AGM packet. Thus, this most recent AGM could contain >> - * either the same old slot 1 or the new slot 2. >> - * Subsequent AGMs will be reporting slot 2. >> - * >> - * To userspace, the resulting transition will look like: >> - * 2:[0,1] -> 3:[0,-1] -> 3:[0,2] >> - */ >> - synaptics_mt_state_set(mt_state, 3, 0, -1); >> - break; >> - case 3: >> - /* >> - * If, for whatever reason, the previous agm was invalid, >> - * Assume SGM now contains slot 0, AGM now contains slot 2. >> - */ >> - if (old->agm <= 2) >> - synaptics_mt_state_set(mt_state, 3, 0, 2); >> - /* >> - * mt_state either hasn't changed, or was updated by a recently >> - * received AGM-CONTACT packet. >> - */ >> - break; >> - >> - case 4: >> - case 5: >> - /* mt_state was updated by AGM-CONTACT packet */ >> - break; >> - } >> -} >> - >> -/* Handle case where mt_state->count = 4, or = 5 */ >> -static void synaptics_image_sensor_45f(struct synaptics_data *priv, >> - struct synaptics_mt_state *mt_state) >> -{ >> - /* mt_state was updated correctly by AGM-CONTACT packet */ >> - priv->mt_state_lost = false; >> -} >> - >> static void synaptics_image_sensor_process(struct psmouse *psmouse, >> struct synaptics_hw_state *sgm) >> { >> struct synaptics_data *priv = psmouse->private; >> - struct synaptics_hw_state *agm = &priv->agm; >> - struct synaptics_mt_state mt_state; >> - >> - /* Initialize using current mt_state (as updated by last agm) */ >> - mt_state = agm->mt_state; >> + int num_fingers; >> >> /* >> * Update mt_state using the new finger count and current mt_state. >> */ >> if (sgm->z == 0) >> - synaptics_image_sensor_0f(priv, &mt_state); >> + num_fingers = 0; >> else if (sgm->w >= 4) >> - synaptics_image_sensor_1f(priv, &mt_state); >> + num_fingers = 1; >> else if (sgm->w == 0) >> - synaptics_image_sensor_2f(priv, &mt_state); >> - else if (sgm->w == 1 && mt_state.count <= 3) >> - synaptics_image_sensor_3f(priv, &mt_state); >> + num_fingers = 2; >> + else if (sgm->w == 1) >> + num_fingers = priv->agm_count ? priv->agm_count : 3; >> else >> - synaptics_image_sensor_45f(priv, &mt_state); >> + num_fingers = 4; >> >> /* Send resulting input events to user space */ >> - synaptics_report_mt_data(psmouse, &mt_state, sgm); >> - >> - /* Store updated mt_state */ >> - priv->mt_state = agm->mt_state = mt_state; >> - priv->agm_pending = false; >> + synaptics_report_mt_data(psmouse, sgm, num_fingers); >> } >> >> static void synaptics_profile_sensor_process(struct psmouse *psmouse, >> @@ -1439,7 +1108,7 @@ static void set_input_params(struct psmouse *psmouse, >> ABS_MT_POSITION_Y); >> /* Image sensors can report per-contact pressure */ >> input_set_abs_params(dev, ABS_MT_PRESSURE, 0, 255, 0, 0); >> - input_mt_init_slots(dev, 2, INPUT_MT_POINTER); >> + input_mt_init_slots(dev, 2, INPUT_MT_POINTER | INPUT_MT_TRACK); >> >> /* Image sensors can signal 4 and 5 finger clicks */ >> __set_bit(BTN_TOOL_QUADTAP, dev->keybit); >> diff --git a/drivers/input/mouse/synaptics.h b/drivers/input/mouse/synaptics.h >> index 1bd01f2..6faf9bb 100644 >> --- a/drivers/input/mouse/synaptics.h >> +++ b/drivers/input/mouse/synaptics.h >> @@ -119,16 +119,6 @@ >> #define SYN_REDUCED_FILTER_FUZZ 8 >> >> /* >> - * A structure to describe which internal touchpad finger slots are being >> - * reported in raw packets. >> - */ >> -struct synaptics_mt_state { >> - int count; /* num fingers being tracked */ >> - int sgm; /* which slot is reported by sgm pkt */ >> - int agm; /* which slot is reported by agm pkt*/ >> -}; >> - >> -/* >> * A structure to describe the state of the touchpad hardware (buttons and pad) >> */ >> struct synaptics_hw_state { >> @@ -143,9 +133,6 @@ struct synaptics_hw_state { >> unsigned int down:1; >> unsigned char ext_buttons; >> signed char scroll; >> - >> - /* As reported in last AGM-CONTACT packets */ >> - struct synaptics_mt_state mt_state; >> }; >> >> struct synaptics_data { >> @@ -170,15 +157,12 @@ struct synaptics_data { >> >> struct serio *pt_port; /* Pass-through serio port */ >> >> - struct synaptics_mt_state mt_state; /* Current mt finger state */ >> - bool mt_state_lost; /* mt_state may be incorrect */ >> - >> /* >> * Last received Advanced Gesture Mode (AGM) packet. An AGM packet >> * contains position data for a second contact, at half resolution. >> */ >> struct synaptics_hw_state agm; >> - bool agm_pending; /* new AGM packet received */ >> + unsigned int agm_count; /* finger count reported by agm */ >> >> /* ForcePad handling */ >> unsigned long press_start; >> -- >> 2.1.0 >> > > -- > Dmitry > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/