From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH] touchscreen: sun4i-ts: Really fix A10 temperature reporting Date: Tue, 23 Jun 2015 12:54:24 -0700 Message-ID: <20150623195424.GE40168@dtor-ws> References: <1425893870-28715-1-git-send-email-hdegoede@redhat.com> <41a7a857-96fd-48ab-9778-127cfc091ef0@googlegroups.com> <5589B78C.4080600@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <5589B78C.4080600-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Hans de Goede Cc: m.silentcreek-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, wens-jdAy2FN1RRM@public.gmane.org, maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org List-Id: devicetree@vger.kernel.org On Tue, Jun 23, 2015 at 09:46:20PM +0200, Hans de Goede wrote: > Hi, >=20 > On 06/23/2015 05:06 PM, m.silentcreek-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote: > >Hi Hans, > > > >is it possible that this patch (and the parent commit "Input: sun4i-= ts - allow controlling filter and sensitivity via DT") has quite an adv= ersial effect on other boards than the ones tested? > > > >On my Lemaker Bananapi the temperature is now being reported as somw= here between -15=B0C to -10=B0C with the latest Kernel 4.1.0. These neg= ative values are obviously way off. On Kernel 4.0.5 the temperature rea= ding was usually around 40=B0C. While that might not have been accurate= either, it was at least plausible. >=20 > The temperature curve for the A20 SoC was not changed, if it did chan= ge then > you're using an old dtb file with a new kernel, you must always updat= e your > dtb file together with the kernel. Umm, we should keep compatibility with old DTS... >=20 >=20 >=20 > > > >Given that there is no Documentation and things seem quite board-spe= cific, I really don't know how this could be improved, so I can merely = report my observation. > > > >Kind regards, > > > >Timo > > > > > >Am Montag, 9. M=E4rz 2015 10:38:02 UTC+1 schrieb Hans de Goede: > >>The commit titled: > >>"touchscreen: sun4i-ts: A10 (sun4i) has a different temperature cur= ve" > >>contains a math error, the offset it uses is in degrees, but the ac= tual 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 co= mmit > >>fixes things by changing the code applying the offset to do the log= ical > >>thing, adjusting the offset for the other models accordingly. > >> > >>This has been tested on an A10, A13, A20 and A31 to make sure every= thing 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 cur= ve" > >>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/t= ouchscreen/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_dev= ice *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_dev= ice *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 > > >=20 > Regards, >=20 > Hans --=20 Dmitry -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html