From: "Pandruvada, Srinivas" <srinivas.pandruvada@intel.com> To: "pmeerw@pmeerw.net" <pmeerw@pmeerw.net> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>, "Tirdea, Irina" <irina.tirdea@intel.com>, "jic23@kernel.org" <jic23@kernel.org>, "Reus, Adriana" <adriana.reus@intel.com> Subject: Re: [PATCH 2/2] iio: accel: kxcjk-1013: optimize i2c transfers in trigger handler Date: Fri, 20 Feb 2015 15:27:43 +0000 [thread overview] Message-ID: <1424446063.2916.17.camel@spandruv-mobl2> (raw) In-Reply-To: <alpine.DEB.2.02.1502201621430.2739@pmeerw.net> [-- Warning: decoded text below may be mangled, UTF-8 assumed --] [-- Attachment #1: Type: text/plain; charset="utf-8", Size: 1372 bytes --] On Fri, 2015-02-20 at 16:23 +0100, Peter Meerwald wrote: > > > > > + > > > > > + values[i] = data & 0xFF; > > > > > + values[i+1] = data >> 8; > > > > > > > > this is incorrect; it forces the data to be little endian, however, the > > > > endianness (as specified in the driver's .scan_type) is IIO_CPU -- the > > > > code breaks for big-endian CPUs > > > > > > > > since _read_i2c_block_data() can't do endianness conversion (and the chip > > > > does i2c endianness, i.e. little-endian), the .scan_type should become > > > > IIO_LE and above code is correct again but still ugly :) > > > > > > > > bottom line: change .scan_type to IIO_LE > > > > > > > Good point. Changing the endianess to IIO_LE is correct for either kxcjk1013_read_block_data or i2c_smbus_read_i2c_block_data. > > > Will fix this in the next version. Thanks for catching this! > > > > > I don't think changing to IIO_LE is good idea as when i2c_read_bock.. > > then the scan type will be CPU. So better to fix endianness in this > > function. > > the chip has little-endian data registers; i2c_read_block() just transfers > the data (no endianness conversion), so the data will still be > little-endian You are right. > > p. > ÿôèº{.nÇ+·®+%Ëÿ±éݶ\x17¥wÿº{.nÇ+·¥{±þG«éÿ{ayº\x1dÊÚë,j\a¢f£¢·hïêÿêçz_è®\x03(éÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?¨èÚ&£ø§~á¶iOæ¬z·vØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?I¥
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From: "Pandruvada, Srinivas" <srinivas.pandruvada@intel.com> To: "pmeerw@pmeerw.net" <pmeerw@pmeerw.net> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>, "Tirdea, Irina" <irina.tirdea@intel.com>, "jic23@kernel.org" <jic23@kernel.org>, "Reus, Adriana" <adriana.reus@intel.com> Subject: Re: [PATCH 2/2] iio: accel: kxcjk-1013: optimize i2c transfers in trigger handler Date: Fri, 20 Feb 2015 15:27:43 +0000 [thread overview] Message-ID: <1424446063.2916.17.camel@spandruv-mobl2> (raw) In-Reply-To: <alpine.DEB.2.02.1502201621430.2739@pmeerw.net> T24gRnJpLCAyMDE1LTAyLTIwIGF0IDE2OjIzICswMTAwLCBQZXRlciBNZWVyd2FsZCB3cm90ZToN Cj4gPiA+ID4gPiArDQo+ID4gPiA+ID4gKwkJdmFsdWVzW2ldID0gZGF0YSAmIDB4RkY7DQo+ID4g PiA+ID4gKwkJdmFsdWVzW2krMV0gPSBkYXRhID4+IDg7DQo+ID4gPiA+IA0KPiA+ID4gPiB0aGlz IGlzIGluY29ycmVjdDsgaXQgZm9yY2VzIHRoZSBkYXRhIHRvIGJlIGxpdHRsZSBlbmRpYW4sIGhv d2V2ZXIsIHRoZQ0KPiA+ID4gPiBlbmRpYW5uZXNzIChhcyBzcGVjaWZpZWQgaW4gdGhlIGRyaXZl cidzIC5zY2FuX3R5cGUpIGlzIElJT19DUFUgLS0gdGhlDQo+ID4gPiA+IGNvZGUgYnJlYWtzIGZv ciBiaWctZW5kaWFuIENQVXMNCj4gPiA+ID4gDQo+ID4gPiA+IHNpbmNlIF9yZWFkX2kyY19ibG9j a19kYXRhKCkgY2FuJ3QgZG8gZW5kaWFubmVzcyBjb252ZXJzaW9uIChhbmQgdGhlIGNoaXANCj4g PiA+ID4gZG9lcyBpMmMgZW5kaWFubmVzcywgaS5lLiBsaXR0bGUtZW5kaWFuKSwgdGhlIC5zY2Fu X3R5cGUgc2hvdWxkIGJlY29tZQ0KPiA+ID4gPiBJSU9fTEUgYW5kIGFib3ZlIGNvZGUgaXMgY29y cmVjdCBhZ2FpbiBidXQgc3RpbGwgdWdseSA6KQ0KPiA+ID4gPiANCj4gPiA+ID4gYm90dG9tIGxp bmU6IGNoYW5nZSAuc2Nhbl90eXBlIHRvIElJT19MRQ0KPiA+ID4gPiANCj4gPiA+IEdvb2QgcG9p bnQuIENoYW5naW5nIHRoZSBlbmRpYW5lc3MgdG8gSUlPX0xFIGlzIGNvcnJlY3QgZm9yIGVpdGhl ciBreGNqazEwMTNfcmVhZF9ibG9ja19kYXRhIG9yIGkyY19zbWJ1c19yZWFkX2kyY19ibG9ja19k YXRhLg0KPiA+ID4gV2lsbCBmaXggdGhpcyBpbiB0aGUgbmV4dCB2ZXJzaW9uLiBUaGFua3MgZm9y IGNhdGNoaW5nIHRoaXMhDQo+ID4gPiANCj4gPiBJIGRvbid0IHRoaW5rIGNoYW5naW5nIHRvIElJ T19MRSBpcyBnb29kIGlkZWEgYXMgd2hlbiBpMmNfcmVhZF9ib2NrLi4NCj4gPiB0aGVuIHRoZSBz Y2FuIHR5cGUgd2lsbCBiZSBDUFUuIFNvIGJldHRlciB0byBmaXggZW5kaWFubmVzcyBpbiB0aGlz DQo+ID4gZnVuY3Rpb24uDQo+IA0KPiB0aGUgY2hpcCBoYXMgbGl0dGxlLWVuZGlhbiBkYXRhIHJl Z2lzdGVyczsgaTJjX3JlYWRfYmxvY2soKSBqdXN0IHRyYW5zZmVycyANCj4gdGhlIGRhdGEgKG5v IGVuZGlhbm5lc3MgY29udmVyc2lvbiksIHNvIHRoZSBkYXRhIHdpbGwgc3RpbGwgYmUgDQo+IGxp dHRsZS1lbmRpYW4NCllvdSBhcmUgcmlnaHQuDQo+IA0KPiBwLg0KPiANCg0K
next prev parent reply other threads:[~2015-02-20 15:27 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-02-16 18:21 [PATCH 0/2] kxcjk-1013 driver optimizations Irina Tirdea 2015-02-16 18:21 ` [PATCH 1/2] iio: accel: kxcjk-1013: use available_scan_masks Irina Tirdea 2015-02-16 18:21 ` [PATCH 2/2] iio: accel: kxcjk-1013: optimize i2c transfers in trigger handler Irina Tirdea 2015-02-16 19:26 ` Peter Meerwald 2015-02-20 12:02 ` Tirdea, Irina 2015-02-20 12:02 ` Tirdea, Irina 2015-02-20 14:58 ` Pandruvada, Srinivas 2015-02-20 14:58 ` Pandruvada, Srinivas 2015-02-20 15:23 ` Peter Meerwald 2015-02-20 15:27 ` Pandruvada, Srinivas [this message] 2015-02-20 15:27 ` Pandruvada, Srinivas 2015-02-21 18:29 ` Jonathan Cameron 2015-02-24 17:25 ` Tirdea, Irina 2015-02-24 17:25 ` Tirdea, Irina 2015-02-16 19:14 ` [PATCH 0/2] kxcjk-1013 driver optimizations Peter Meerwald 2015-02-20 12:03 ` Tirdea, Irina 2015-02-21 18:26 ` Jonathan Cameron 2015-02-24 17:22 ` Tirdea, Irina
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