From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [PATCH] touchscreen: sun4i-ts: Really fix A10 temperature reporting Date: Tue, 23 Jun 2015 21:46:20 +0200 Message-ID: <5589B78C.4080600@redhat.com> References: <1425893870-28715-1-git-send-email-hdegoede@redhat.com> <41a7a857-96fd-48ab-9778-127cfc091ef0@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41130 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754461AbbFWTqX (ORCPT ); Tue, 23 Jun 2015 15:46:23 -0400 In-Reply-To: <41a7a857-96fd-48ab-9778-127cfc091ef0@googlegroups.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: m.silentcreek@gmail.com, linux-sunxi@googlegroups.com Cc: linux-input@vger.kernel.org, dmitry.torokhov@gmail.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wens@csie.org, maxime.ripard@free-electrons.com Hi, On 06/23/2015 05:06 PM, m.silentcreek@gmail.com wrote: > Hi Hans, > > is it possible that this patch (and the parent commit "Input: sun4i-t= s - allow controlling filter and sensitivity via DT") has quite an adve= rsial effect on other boards than the ones tested? > > On my Lemaker Bananapi the temperature is now being reported as somwh= ere between -15=C2=B0C to -10=C2=B0C with the latest Kernel 4.1.0. Thes= e negative values are obviously way off. On Kernel 4.0.5 the temperatur= e reading was usually around 40=C2=B0C. While that might not have been = accurate either, it was at least plausible. The temperature curve for the A20 SoC was not changed, if it did change= then you're using an old dtb file with a new kernel, you must always update = your dtb file together with the kernel. > > Given that there is no Documentation and things seem quite board-spec= ific, I really don't know how this could be improved, so I can merely r= eport my observation. > > Kind regards, > > Timo > > > Am Montag, 9. M=C3=A4rz 2015 10:38:02 UTC+1 schrieb Hans de Goede: >> The commit titled: >> "touchscreen: sun4i-ts: A10 (sun4i) has a different temperature curv= e" >> contains a math error, the offset it uses is in degrees, but the act= ual code >> applies the offset before multiplying by stepsize :| >> >> Given that this is rather backwards (every math course ever thought = applies >> the multiplication before the offset for linear functions), this com= mit >> fixes things by changing the code applying the offset to do the logi= cal >> thing, adjusting the offset for the other models accordingly. >> >> This has been tested on an A10, A13, A20 and A31 to make sure everyt= hing really >> is correct now. >> >> Signed-off-by: Hans de Goede >> --- >> Note if possible this commit should be squashed into the original >> "touchscreen: sun4i-ts: A10 (sun4i) has a different temperature curv= e" >> commit as a fixup. >> --- >> drivers/input/touchscreen/sun4i-ts.c | 14 +++++++------- >> 1 file changed, 7 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/input/touchscreen/sun4i-ts.c b/drivers/input/to= uchscreen/sun4i-ts.c >> index 66ccd5a..178d2ef 100644 >> --- a/drivers/input/touchscreen/sun4i-ts.c >> +++ b/drivers/input/touchscreen/sun4i-ts.c >> @@ -193,7 +193,7 @@ static int sun4i_get_temp(const struct sun4i_ts_= data *ts, long *temp) >> if (ts->temp_data =3D=3D -1) >> return -EAGAIN; >> >> - *temp =3D (ts->temp_data - ts->temp_offset) * ts->temp_step; >> + *temp =3D ts->temp_data * ts->temp_step - ts->temp_offset; >> >> return 0; >> } >> @@ -255,17 +255,17 @@ static int sun4i_ts_probe(struct platform_devi= ce *pdev) >> ts->ignore_fifo_data =3D true; >> ts->temp_data =3D -1; >> if (of_device_is_compatible(np, "allwinner,sun6i-a31-ts")) { >> - /* Allwinner SDK has temperature =3D -271 + (value / 6) (C) */ >> - ts->temp_offset =3D 1626; >> + /* Allwinner SDK has temperature (C) =3D (value / 6) - 271 */ >> + ts->temp_offset =3D 271000; >> ts->temp_step =3D 167; >> } else if (of_device_is_compatible(np, "allwinner,sun4i-a10-ts"))= { >> /* >> * The A10 temperature sensor has quite a wide spread, these >> * parameters are based on the averaging of the calibration >> * results of 4 completely different boards, with a spread of >> - * temp_step from 96 - 170 and temp_offset from 1758 - 3310. >> + * temp_step from 0.096 - 0.170 and temp_offset from 176 - 331. >> */ >> - ts->temp_offset =3D 2570; >> + ts->temp_offset =3D 257000; >> ts->temp_step =3D 133; >> } else { >> /* >> @@ -273,13 +273,13 @@ static int sun4i_ts_probe(struct platform_devi= ce *pdev) >> * the temperature. The formula used here is from the AXP209, >> * which is designed by X-Powers, an affiliate of Allwinner: >> * >> - * temperature =3D -144.7 + (value * 0.1) >> + * temperature (C) =3D (value * 0.1) - 144.7 >> * >> * Allwinner does not have any documentation whatsoever for >> * this hardware. Moreover, it is claimed that the sensor >> * is inaccurate and cannot work properly. >> */ >> - ts->temp_offset =3D 1447; >> + ts->temp_offset =3D 144700; >> ts->temp_step =3D 100; >> } >> >> -- >> 2.3.1 > Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-input" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html