From: Guenter Roeck <linux@roeck-us.net>
To: Mike Jones <michael-a1.jones@analog.com>
Cc: linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
jdelvare@suse.com, robh+dt@kernel.org, corbet@lwn.net
Subject: Re: [PATCH 2/3] hwmon: (pmbus/ltc2978): Fix PMBus polling of MFR_COMMON definitions.
Date: Tue, 28 Jan 2020 11:13:06 -0800 [thread overview]
Message-ID: <20200128191306.GA32672@roeck-us.net> (raw)
In-Reply-To: <1580234400-2829-2-git-send-email-michael-a1.jones@analog.com>
On Tue, Jan 28, 2020 at 10:59:59AM -0700, Mike Jones wrote:
> Change 21537dc driver PMBus polling of MFR_COMMON from bits 5/4 to
> bits 6/5. This fixs a LTC297X family bug where polling always returns
> not busy even when the part is busy. This fixes a LTC388X and
> LTM467X bug where polling used PEND and NOT_IN_TRANS, and BUSY was
> not polled, which can lead to NACKing of commands. LTC388X and
> LTM467X modules now poll BUSY and PEND, increasing reliability by
> eliminating NACKing of commands.
>
> Signed-off-by: Mike Jones <michael-a1.jones@analog.com>
Fixes: e04d1ce9bbb49 ("hwmon: (ltc2978) Add polling for chips requiring it")
> ---
> drivers/hwmon/pmbus/ltc2978.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/pmbus/ltc2978.c b/drivers/hwmon/pmbus/ltc2978.c
> index f01f488..a91ed01 100644
> --- a/drivers/hwmon/pmbus/ltc2978.c
> +++ b/drivers/hwmon/pmbus/ltc2978.c
> @@ -82,8 +82,8 @@ enum chips { ltc2974, ltc2975, ltc2977, ltc2978, ltc2980, ltc3880, ltc3882,
>
> #define LTC_POLL_TIMEOUT 100 /* in milli-seconds */
>
> -#define LTC_NOT_BUSY BIT(5)
> -#define LTC_NOT_PENDING BIT(4)
> +#define LTC_NOT_BUSY BIT(6)
> +#define LTC_NOT_PENDING BIT(5)
>
In ltc_wait_ready(), we have:
/*
* LTC3883 does not support LTC_NOT_PENDING, even though
* the datasheet claims that it does.
*/
mask = LTC_NOT_BUSY;
if (data->id != ltc3883)
mask |= LTC_NOT_PENDING;
The semantics of this code is now different: It means that on
LTC3883 only bit 6 is checked; previously, it was bit 5. I agree
that the above change makes sense, but it doesn't seem correct
to drop the check for bit 5 on LTC3883. Maybe remove the if() above
and always check for bit 5 and 6 ? Or should bit 4 be checked
on parts other than LTC3883 ?
#define LTC_NOT_TRANSITIONING BIT(4)
...
mask = LTC_NOT_BUSY | LTC_NOT_PENDING;
if (data->id != ltc3883)
mask |= LTC_NOT_TRANSITIONING;
Thanks,
Guenter
next prev parent reply other threads:[~2020-01-28 19:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 17:59 [PATCH 1/3] docs: hwmon: (pmbus/ltc2978): Update datasheet URLs to analog.com Mike Jones
2020-01-28 17:59 ` [PATCH 2/3] hwmon: (pmbus/ltc2978): Fix PMBus polling of MFR_COMMON definitions Mike Jones
2020-01-28 19:13 ` Guenter Roeck [this message]
2020-01-28 21:16 ` Jones, Michael-A1
2020-01-28 21:31 ` Guenter Roeck
2020-01-28 21:35 ` Jones, Michael-A1
2020-01-28 22:38 ` Guenter Roeck
2020-01-28 18:00 ` [PATCH 3/3] hwmon: (pmbus/ltc2978): add support for more parts Mike Jones
2020-02-06 17:12 ` Rob Herring
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