Hi Hannes, On Tuesday 14 April 2015 04:46 PM, Hannes Petermaier wrote: > Hi Vignesh, > > did you recognize my last email ? whats your opinion around that = > > best regards, > Hannes > ----- Forwarded by Hannes Petermaier/Eggelsberg/AT/B&R on 14.04.2015 13:14 > ----- > > Hannes Petermaier/Eggelsberg/AT/B&R schrieb am 07.04.2015 14:30:19: > >> From: Hannes Petermaier/Eggelsberg/AT/B&R >> To: vigne...@ti.com >> Cc: linux-...@vger.kernel.org >> Date: 07.04.2015 14:30 >> Subject: WG: Fwd: [PATCH 0/2] iio: ti_am335x_adc: Add optional DT > properties for tscadc >> >> Hi Vignesh, >> >> would it be possible to add some more channel-specific settings ? >> >> It would be nice to have allmost full control to the STEPCONFIGx > register. >> >> At least we need to write the bits >> >> SEL_RFM_SWC_1_0 >> SEL_INM_SWC_3_0 >> SEL_RFP_SWC_2_0 >> >> In the current mainline version only (SEL_INP_SWC_3_0) is written. >> So for the other bits "0" is value is used, for my point of view this is > not correct. >> >> For example if we want to read a value from AIN5 the negative pin from > adc is >> muxed allways to AIN0.
Sorry... I didn't understand what you meant by"AIN5 is muxed always with AIN0"? >> In fact i can readout heavy jitter even if AIN5 is connected to ground - > after >> setting up negative adc pin within code (to use REFN) the readout value > is 0 >> as expected without nameable jitter. >> If i short AIN0 also to ground, jitter is also eliminated. Hmmm... nobody has reported such behavior before. ADC support for am335x-evm/beaglebone has been there for quite long time, but nobody reported any jitter on AIN5 line. I think this may be specific to your setup. Can you provide more info with regard to your setup? Which kernel? Is it am335x-evm or beaglebone or a custom board? >> >> Maybe this is also some fault of TI SoC ... in normal case somebody > could >> expect, that negative adc pin is equal even the Diff_CNTRL bit isn't set > - but >> in practice it isn't. >> >> Also actually it isn't possible to make some accurate measurement due to > the >> fact that allways VDDA_ADC is used as positive reference. >> >> So it would be nice to have control around this bits. >> Whats your opinion around that? Sorry, I am not yet clear on your bug/use-case. Please comment inline while replying on mailing list Regards Vignesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
