From: Anson Huang <anson.huang@nxp.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>,
"rui.zhang@intel.com" <rui.zhang@intel.com>,
"amit.kucheria@verdurent.com" <amit.kucheria@verdurent.com>,
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"festevam@gmail.com" <festevam@gmail.com>,
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"will@kernel.org" <will@kernel.org>,
Leonard Crestez <leonard.crestez@nxp.com>,
Daniel Baluta <daniel.baluta@nxp.com>,
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Cc: dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH RESEND 2/4] thermal: imx8mm: Add support for i.MX8MM thermal monitoring unit
Date: Sat, 29 Feb 2020 03:37:02 +0000 [thread overview]
Message-ID: <DB3PR0402MB39160BF1E6FDF0990E462708F5E90@DB3PR0402MB3916.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <07994b0e-9735-2f3e-e5c3-a57e2344dbc0@linaro.org>
Hi, Daniel
> Subject: Re: [PATCH RESEND 2/4] thermal: imx8mm: Add support for
> i.MX8MM thermal monitoring unit
>
> On 28/02/2020 02:12, Anson Huang wrote:
> > Hi, Daniel
>
> [ ... ]
>
> >>> +static int tmu_get_temp(void *data, int *temp) {
> >>> + struct imx8mm_tmu *tmu = data;
> >>> + u32 val;
> >>> +
> >>> + /* the temp sensor need about 1ms to finish the measurement */
> >>> + usleep_range(1000, 2000);
> >>
> >> Why do yo need to force a delay here? If the sensor can not be read
> >> more than one time every 1ms, then specify that in the DT switching
> >> the polling to the right value, no?
> >
> > The polling time(2 seconds) is OK for this case, adding this sleep is
> > to prevent user from reading temperature from sysfs interface very
> frequently like less than 1ms, does it make sense?
>
> Not really, well except if the user is able to press the keys in less than 1ms :)
>
> If the userspace writes a polling script reading the temperature in a busy loop,
> there is nothing we can do against silly programming :/
Make sense😊
>
> However, it could interesting to add a <min polling interval> in the thermal
> structure and handle that from the core framework by caching the last value
> and return it in case get_temp is called too fast.
OK, I will resend V2 patch set to remove the sleep in this driver and see if there is
real issue of such corner case, if any issue observed, I will try summit a patch to core
framework later.
Thanks,
Anson
next prev parent reply other threads:[~2020-02-29 3:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 8:17 [PATCH RESEND 1/4] dt-bindings: thermal: imx8mm-thermal: Add binding doc for i.MX8MM Anson Huang
2020-02-20 8:17 ` [PATCH RESEND 2/4] thermal: imx8mm: Add support for i.MX8MM thermal monitoring unit Anson Huang
2020-02-27 11:07 ` Daniel Lezcano
2020-02-28 1:12 ` Anson Huang
2020-02-28 9:31 ` Daniel Lezcano
2020-02-29 3:37 ` Anson Huang [this message]
2020-02-20 8:17 ` [PATCH RESEND 3/4] arm64: defconfig: Enable CONFIG_IMX8MM_THERMAL as module Anson Huang
2020-02-20 8:17 ` [PATCH RESEND 4/4] arm64: dts: imx8mm: Add thermal zone support Anson Huang
-- strict thread matches above, loose matches on Subject: below --
2019-10-28 6:03 [PATCH RESEND 1/4] dt-bindings: thermal: imx8mm-thermal: Add binding doc for i.MX8MM Anson Huang
2019-10-28 6:03 ` [PATCH RESEND 2/4] thermal: imx8mm: Add support for i.MX8MM thermal monitoring unit Anson Huang
2019-10-29 10:26 ` Fabio Estevam
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