On Mon, 18 Sep 2023 09:52:20 +1000 Alexander Zangerl <az@xxxxxxxxxxxxxxxx> wrote: > the ms5611 driver falsely rejects lots of MS5607-02BA03-50 chips > with "PROM integrity check failed" because it doesn't accept a prom crc > value of zero as legitimate. > > according to the datasheet for this chip (and the manufacturer's > application note about the prom crc), none of the possible > values for the crc are excluded - but the current code > in ms5611_prom_is_valid() ends with > > return crc_orig != 0x0000 && crc == crc_orig > > datasheet: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=MS5607-02BA03&DocType=Data+Sheet&DocLang=English > application note: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=AN520_C-code_example_for_MS56xx&DocType=SS&DocLang=EN > > i've discussed this whith the original author of the driver (tomasz > duszynski) and he indicated that at that time (2015) he was dealing with > some faulty chip samples which returned blank data under some > circumstances and/or followed example code which indicated crc zero > being bad (i can't find any traces of any such online, however). > > as far as i can tell this exception should not be applied anymore; we've > got a few hundred custom boards here with this chip where large numbers > of the prom have a legitimate crc value 0, and do work fine, but which the > current driver code wrongly rejects. > > (i can provide some example prom dumps if required.) > > the attached tiny patch is against 4.19. but that > section of the code is unchanged up to and including 6.6. > > > From 653b5cf063e07d126e67386b152e4e76d4f8c1dc Mon Sep 17 00:00:00 2001 > From: Alexander Zangerl <az@xxxxxxxxxxxxxxxx> > Date: Mon, 18 Sep 2023 09:44:00 +1000 > Subject: [PATCH] ms5611: crc zero is valid and should not be rejected Please resend with this formatting as a patch, so the above should be in a cover letter with this sent in reply to that. git format-patch --cover-letter will set it it up right. Needs a Signed-off-by and Fixes tag as well before I can take this. Otherwise, description all makes sense so good to get this fix in place. Jonathan > > --- > drivers/iio/pressure/ms5611_core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c > index 5c7a734ede54..9980c6f3335e 100644 > --- a/drivers/iio/pressure/ms5611_core.c > +++ b/drivers/iio/pressure/ms5611_core.c > @@ -79,7 +79,7 @@ static bool ms5611_prom_is_valid(u16 *prom, size_t len) > > crc = (crc >> 12) & 0x000F; > > - return crc_orig != 0x0000 && crc == crc_orig; > + return crc == crc_orig; > } > > static int ms5611_read_prom(struct iio_dev *indio_dev) > -- > 2.30.2 > > > > Best Regards, > Alexander Zangerl > IT Engineer > > -- > P +61 7 3276 7833 | M +61 415 482 341 > E az@xxxxxxxxxxxxxxxx | W breathe-safe.com.au > A 62 Mica Street, Carole Park, 4300, QLD
