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From: Dipen Patel <dipenp@nvidia.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: "thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	Jon Hunter <jonathanh@nvidia.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-tegra <linux-tegra@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Kent Gibson <warthog618@gmail.com>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>
Subject: Re: [RFC 08/11] gpiolib: cdev: Add hardware timestamp clock type
Date: Thu, 29 Jul 2021 20:16:04 -0700	[thread overview]
Message-ID: <2bfbb684-d9d3-8779-11fe-6b4152f114d6@nvidia.com> (raw)
In-Reply-To: <CACRpkdb-AFvLhwOLSs5ocqiZ6ZwZbQMzWGfQ6C3AX+=ouH+=ng@mail.gmail.com>


On 6/27/21 4:49 AM, Linus Walleij wrote:
> On Sat, Jun 26, 2021 at 1:48 AM Dipen Patel <dipenp@nvidia.com> wrote:
>
> Just a quick question about this:
>
>> +        GPIO_V2_LINE_FLAG_EVENT_CLOCK_HARDWARE | \
> Is the usage intended to be such that since hardware timestamp
> can not be guaranteed we need to ask for it and fail and if that
> fails maybe the software wants to fall back to the realtime or
> common timestamp?
>
> I'm thinking from the view of libgpiod or similar apps that abstract
> this and they will be "I want to use hardware timestamps if and
> only if it is available, otherwise I want to use this other timestamp"
> or is that use case uncommon, such that either you know exactly
> what you want or you should not be messing with hardware
> timestamps?


The way currently is implemented, if you have requested

FLAG_EVENT_CLOCK_HARDWARE and it fails, control will return

to userspace with an error. There is no fallback.

>
> Yours,
> Linus Walleij

  reply	other threads:[~2021-07-30  3:07 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-25 23:55 [RFC 00/11] Intro to Hardware timestamping engine Dipen Patel
2021-06-25 23:55 ` [RFC 01/11] Documentation: Add HTE subsystem guide Dipen Patel
2021-07-04 18:55   ` Jonathan Cameron
2021-07-27 23:44     ` Dipen Patel
2021-08-01 15:24       ` Jonathan Cameron
2021-06-25 23:55 ` [RFC 02/11] drivers: Add HTE subsystem Dipen Patel
2021-06-27 17:40   ` Randy Dunlap
2021-07-04 20:15   ` Jonathan Cameron
2021-07-04 20:45     ` Jonathan Cameron
2021-07-28  5:12       ` Dipen Patel
2021-08-01 16:48         ` Jonathan Cameron
2021-07-28  4:38     ` Dipen Patel
2021-08-01 16:13       ` Jonathan Cameron
2021-09-14  5:43         ` Dipen Patel
2021-09-26 15:42           ` Jonathan Cameron
2021-07-05  7:30   ` Greg KH
2021-07-28  0:34     ` Dipen Patel
2021-06-25 23:55 ` [RFC 03/11] hte: Add tegra194 HTE kernel provider Dipen Patel
2021-07-01 14:21   ` Kent Gibson
2021-07-28 23:59     ` Dipen Patel
2021-07-30  7:01       ` Dipen Patel
2021-07-31 15:43       ` Kent Gibson
2021-08-03 22:40         ` Dipen Patel
2021-08-03 23:02           ` Kent Gibson
2021-08-07  2:41         ` Dipen Patel
2021-08-07  3:07           ` Kent Gibson
2021-08-07  4:52             ` Dipen Patel
2021-08-07  4:51               ` Kent Gibson
2021-08-07  5:35                 ` Dipen Patel
2021-08-07  5:42                   ` Kent Gibson
2021-08-07  5:47                   ` Dipen Patel
2021-07-04 20:27   ` Jonathan Cameron
2021-07-29  2:42     ` Dipen Patel
2021-07-08 23:33   ` Michał Mirosław
2021-07-29  2:43     ` Dipen Patel
2021-06-25 23:55 ` [RFC 04/11] dt-bindings: Add HTE bindings Dipen Patel
2021-06-27 10:56   ` Linus Walleij
2021-07-30  1:32     ` Dipen Patel
2021-07-01 14:02   ` Rob Herring
2021-07-30  1:56     ` Dipen Patel
2021-07-01 15:54   ` Rob Herring
2021-07-30  1:58     ` Dipen Patel
2021-06-25 23:55 ` [RFC 05/11] hte: Add Tegra194 IRQ HTE test driver Dipen Patel
2021-06-27 17:42   ` Randy Dunlap
2021-06-25 23:55 ` [RFC 06/11] gpiolib: Add HTE support Dipen Patel
2021-06-27 11:41   ` Linus Walleij
2021-07-01 14:24   ` Kent Gibson
2021-07-30  2:25     ` Dipen Patel
2021-07-31  5:13       ` Kent Gibson
2021-06-25 23:55 ` [RFC 07/11] gpio: tegra186: Add HTE in gpio-tegra186 driver Dipen Patel
2021-06-25 23:55 ` [RFC 08/11] gpiolib: cdev: Add hardware timestamp clock type Dipen Patel
2021-06-27 11:38   ` Linus Walleij
2021-06-27 11:49   ` Linus Walleij
2021-07-30  3:16     ` Dipen Patel [this message]
2021-07-01 14:24   ` Kent Gibson
2021-07-30  3:07     ` Dipen Patel
2021-07-31  6:05       ` Kent Gibson
2021-08-03 22:41         ` Dipen Patel
2021-08-03 22:38           ` Kent Gibson
2021-07-09  8:30   ` Jon Hunter
2021-07-30  2:33     ` Dipen Patel
2021-08-03 16:42       ` Jon Hunter
2021-08-03 22:51         ` Dipen Patel
2021-08-03 23:09           ` Kent Gibson
2021-06-25 23:55 ` [RFC 09/11] tools: gpio: Add new hardware " Dipen Patel
2021-06-27 11:36   ` Linus Walleij
2021-07-30  3:17     ` Dipen Patel
2021-07-31  6:16       ` Kent Gibson
2021-08-11  9:11         ` Linus Walleij
2021-06-25 23:55 ` [RFC 10/11] hte: Add tegra GPIO HTE test driver Dipen Patel
2021-06-27 17:43   ` Randy Dunlap
2021-06-25 23:55 ` [RFC 11/11] MAINTAINERS: Added HTE Subsystem Dipen Patel
2021-06-27 13:07 ` [RFC 00/11] Intro to Hardware timestamping engine Andy Shevchenko
2021-06-27 14:40   ` Linus Walleij
2021-06-28 12:02     ` Andy Shevchenko

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