On Mon, Nov 22, 2021 at 11:16:22AM +0000, [email protected] wrote: > On 11/8/21 5:07 PM, Chris Morgan wrote: > > From: Chris Morgan <[email protected]> > > > > On my NTC CHIP whenever I do a cold boot any attached DIPs cannot be > > found. Rebooting on the other hand appears to fix the issue. I found > > that if I modified the timing slightly (but still within spec) the > > w1 identification on cold boot became far more reliable. > > > > Signed-off-by: Chris Morgan <[email protected]> > > --- > > drivers/w1/w1-gpio.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/w1/w1-gpio.c b/drivers/w1/w1-gpio.c > > index 9346f810ce..5565de2a92 100644 > > --- a/drivers/w1/w1-gpio.c > > +++ b/drivers/w1/w1-gpio.c > > @@ -22,8 +22,8 @@ > > #define W1_TIMING_E 9 > > #define W1_TIMING_F 55 > > #define W1_TIMING_G 0 > > -#define W1_TIMING_H 480 > > -#define W1_TIMING_I 70 > > +#define W1_TIMING_H 600 > > +#define W1_TIMING_I 100 > > #define W1_TIMING_J 410 > > > > struct w1_gpio_pdata { > > -- > > 2.30.2 > > > > > Hi Chris, > > I tested your patch on my board sama5d2_xplained, and it works. > Thus, you can add my > Tested-by: Eugen Hristev <[email protected]> > > However, I disagree with the changes you did in timings. What I found > was that timing 'H' could go up to 640 , but timing 'I' to a maximum of > 75 or so. [1] > > I am thinking maybe you could also check your udelays with a scope on > the 1wire line ? Because your problem might be in fact in some other > part , like udelays not properly aligned/synchronized/accurate at cold > boot time, depending on the source of clock you are using.
I lack a scope, but will extensively test 640 and 75 as the new timings. Would that be acceptable? Thank you. > > Eugen > > > [1] > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.maximintegrated.com%2Fcontent%2Fdam%2Ffiles%2Fdesign%2Ftools%2Ftech-docs%2F126%2FAN126-timing-calculation.zip&data=04%7C01%7C%7C6787b70951c4494fd76808d9ada98a17%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637731765952771191%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=V81HrXrKI8d45WTrvWrc6ydJy2rdCX5%2FL8eYjvxcwCs%3D&reserved=0
