From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: Re: [PATCH v3 21/30] iio: adc: sun4i-gpadc-iio: add support for H3 thermal sensor Date: Wed, 5 Sep 2018 16:58:58 +0200 Message-ID: <20180905145858.4ny5c7xojn7aiwlv@flea> References: <20180830154518.29507-1-embed3d@gmail.com> <20180830154518.29507-22-embed3d@gmail.com> <20180831091137.wkbbipssyd6mqfbt@flea> <20180903102022.fkxfkxadkt4vpbmb@flea> Reply-To: maxime.ripard-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="7e64gxu5f4lvrtxz" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Icenowy Zheng Cc: Philipp Rossak , mark.rutland-5wv7dgnIgG8@public.gmane.org, geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org, linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, clabbe.montjoie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, pmeerw-jW+XmwGofnusTnJN9+BGXg@public.gmane.org, lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org, quentin.schulz-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org, linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org, wens-jdAy2FN1RRM@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, vilhelm.gray-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, rdunlap-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, arnaud.pouliquen-qxv4g6HH51o@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org, knaack.h-Mmb7MZpHnFY@public.gmane.org, eugen.hristev-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org, jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org List-Id: devicetree@vger.kernel.org --7e64gxu5f4lvrtxz Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Sep 03, 2018 at 07:01:47PM +0800, Icenowy Zheng wrote: > =E4=BA=8E 2018=E5=B9=B49=E6=9C=883=E6=97=A5 GMT+08:00 =E4=B8=8B=E5=8D=886= :20:22, Maxime Ripard =E5=86=99=E5=88=B0: > >On Fri, Aug 31, 2018 at 05:51:41PM +0800, Icenowy Zheng wrote: > >> Personally I suggest to leave out all SID or calibration related > >> patches here. > >>=20 > >> Currently we seems to be wrongly converting SID to big endian, > >however, > >> the orgnization of the THS calibration data on H6 shows that it's > >> surely little endian: > >>=20 > >> It consists a temperature value in 1/10 celsuis as unit, and some > >> thermal register readout values, which are the values read out at the > >> given temperature, and every value here (the temperature and the > >> readout) are all half word length. > >>=20 > >> Let the temperature value be AABB, the two readout values be XXYY and > >> ZZWW, the oragnization is: > >> BB AA YY XX WW ZZ ** ** . > >>=20 > >> When converting the SID to big endian, it becomes: > >> XX YY AA BB ** ** ZZ WW , > >> which is non-sense, and not able to do sub-word cell addressing. > >>=20 > >> Maxime, should I drop the LE2BE conversion in SID driver? (I doubt > >> whether it will break compatibility.) > > > >This is exposed to the userspace, so no. >=20 > Please note the LE2BE totally breaks the SID addressing. On which SoCs? > Without it dropped all cells must be referenced with 4 byte word as > unit, and half word addressing of SID is thus not possible. The > driver will also need then to split the half words if needed. >=20 > I think this is kind of hardware misbehavior, and not a simple > UAPI change, so the UAPI stability shouldn't affect this change. How would you feel having your files on your filesystem suddenly not in the same endianness and having all the bytes reordered? This is definitely about the userspace ABI. Maxime --=20 Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --=20 You received this message because you are subscribed to the Google Groups "= linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to linux-sunxi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit https://groups.google.com/d/optout. --7e64gxu5f4lvrtxz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE0VqZU19dR2zEVaqr0rTAlCFNr3QFAluP7zEACgkQ0rTAlCFN r3R3rBAAgLt3ujbBaes4sdzA2oKzSgMlaAi03PkyocmXMXjUdf+H6gKfQsevsOnZ LGan/UQaWN2eie7+bR4+60QYUJMingr+x/rTXUciUGu++UIX9Y25Zj5pckNHk3EB bNmJtIwda1xzs3ShPC9KCnD6wTNHxHYmOBz5/9KhfnDdCa7MyMrpnKlUE5bb1i5q JumaFSCn9fj1Xk+3keAlNUUV6n5q7eONANYawI66elG/7pshzja1BZluBlPqNhqa w/R/BAUKunThRsmfYb0QpxIV8M1fO5yVqYGGy8Hd/bHZVwotmkjtSVBMVDq2+K+C hHnjnKrw//U//wCQ8FiRIwvuL8yZKLDUQNe/XW7RR167BPp92FxgRSKdIhAJD3Ro 3Orii3LRnU7afKNc4X1zx+MxImc2DehSM3lgZWRRpgaRCFUBS/wZAxZoi8KyTreN 5Dr5S/Y5+Fq2xRwIR56awt4Ej8oy0kcs9jElU7zs8m/yj7Q47qpa+GUC6R1tyZt7 cufj2wBJ+XjA7Z5YxpT7IzWs+qO4NLSWwEXUg8kTT18+YEXlV+WSyQku9bxKOhRN H+CSMsAj6UNEidmSyHGtARlIZ1V8dynrPogwsxR4YImxPqtd1ia0an8Uty8Ed8Ua CvHNsf1mabKDrEoVK/zI3ZISIAEVV0nm0mMq96YZiPTpJ9uFmg0= =NYwv -----END PGP SIGNATURE----- --7e64gxu5f4lvrtxz--