From: Andrey Pronin <apronin@chromium.org> To: Rob Herring <robh@kernel.org> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, Peter Huewe <peterhuewe@gmx.de>, Marcel Selhorst <tpmdd@selhorst.net>, Jason Gunthorpe <jgunthorpe@obsidianresearch.com>, tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Christophe Ricard <christophe.ricard@gmail.com>, Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Kumar Gala <galak@codeaurora.org>, devicetree@vger.kernel.org Subject: Re: [PATCH v2 1/2] tpm: devicetree: document properties for cr50 Date: Wed, 20 Jul 2016 12:49:12 -0700 [thread overview] Message-ID: <20160720194912.GA61154@apronin> (raw) In-Reply-To: <20160720190303.GA5620@rob-hp-laptop> On Wed, Jul 20, 2016 at 02:03:03PM -0500, Rob Herring wrote: > On Tue, Jul 19, 2016 at 08:41:24PM -0700, Andrey Pronin wrote: Hi Rob, > As I mentioned, there may be common properties. It doesn't seem you > looked, so I did: > > - spi-rx-delay-us - (optional) Microsecond delay after a read transfer. > - spi-tx-delay-us - (optional) Microsecond delay after a write transfer. > > Seems to me setting one or both of these should work for you. > Yes, good catch, my fault I didn't see those. But they are not exactly what I mean and need. I don't need delay after each read or write transfer. What is needed is a guaranteed time between transfers. So, if the next transaction doesn't come withing the next X ms (or us), we don't waste time on inserting a delays after this transaction at all. Following the description and always inserting a delay must work well for short microseconds-long delays. For longer milliseconds-long delays a different strategy of checking the time when the previous transaction was and only delaying if it was not too long ago is better. Thus, I won't be able to re-use these properties anyways based on their current description in bindings/spi/spi-bus.txt. > > +- sleep-delay-ms: Time after the last SPI activity, after which the chip > > + may go to sleep. > > +- wake-start-delay-ms: Time after initiating wake up before the chip is > > + ready to accept commands over SPI. > > I also asked why these 2 can't be hard-coded in the driver? > Sorry, I just updated this patch description in v2 to indicate why they are not hard-coded, but didn't answer explicitly. As the firmware changes, a different revision of it can have a different time before it sleeps in its configuration, or the time it takes it to startup may be different. Thus, there's a way to set it here w/o changing the driver. Andrey
WARNING: multiple messages have this Message-ID (diff)
From: Andrey Pronin <apronin-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> To: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christophe Ricard <christophe.ricard-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>, Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> Subject: Re: [PATCH v2 1/2] tpm: devicetree: document properties for cr50 Date: Wed, 20 Jul 2016 12:49:12 -0700 [thread overview] Message-ID: <20160720194912.GA61154@apronin> (raw) In-Reply-To: <20160720190303.GA5620@rob-hp-laptop> On Wed, Jul 20, 2016 at 02:03:03PM -0500, Rob Herring wrote: > On Tue, Jul 19, 2016 at 08:41:24PM -0700, Andrey Pronin wrote: Hi Rob, > As I mentioned, there may be common properties. It doesn't seem you > looked, so I did: > > - spi-rx-delay-us - (optional) Microsecond delay after a read transfer. > - spi-tx-delay-us - (optional) Microsecond delay after a write transfer. > > Seems to me setting one or both of these should work for you. > Yes, good catch, my fault I didn't see those. But they are not exactly what I mean and need. I don't need delay after each read or write transfer. What is needed is a guaranteed time between transfers. So, if the next transaction doesn't come withing the next X ms (or us), we don't waste time on inserting a delays after this transaction at all. Following the description and always inserting a delay must work well for short microseconds-long delays. For longer milliseconds-long delays a different strategy of checking the time when the previous transaction was and only delaying if it was not too long ago is better. Thus, I won't be able to re-use these properties anyways based on their current description in bindings/spi/spi-bus.txt. > > +- sleep-delay-ms: Time after the last SPI activity, after which the chip > > + may go to sleep. > > +- wake-start-delay-ms: Time after initiating wake up before the chip is > > + ready to accept commands over SPI. > > I also asked why these 2 can't be hard-coded in the driver? > Sorry, I just updated this patch description in v2 to indicate why they are not hard-coded, but didn't answer explicitly. As the firmware changes, a different revision of it can have a different time before it sleeps in its configuration, or the time it takes it to startup may be different. Thus, there's a way to set it here w/o changing the driver. Andrey ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports.http://sdm.link/zohodev2dev
next prev parent reply other threads:[~2016-07-20 19:49 UTC|newest] Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-15 2:20 [PATCH 0/2] tpm: add driver for cr50 on SPI Andrey Pronin 2016-07-15 2:20 ` [PATCH 1/2] tpm: devicetree: document properties for cr50 Andrey Pronin 2016-07-15 2:20 ` Andrey Pronin 2016-07-15 4:05 ` Guenter Roeck 2016-07-15 17:31 ` Andrey Pronin 2016-07-15 17:31 ` Andrey Pronin 2016-07-15 18:28 ` Guenter Roeck 2016-07-15 18:28 ` Guenter Roeck 2016-07-17 13:28 ` Rob Herring 2016-07-17 13:28 ` Rob Herring 2016-07-15 2:20 ` [PATCH 2/2] tpm: add driver for cr50 on SPI Andrey Pronin 2016-07-15 2:20 ` Andrey Pronin 2016-07-15 3:32 ` Jason Gunthorpe 2016-07-15 3:32 ` Jason Gunthorpe 2016-07-15 3:44 ` Andrey Pronin 2016-07-15 3:44 ` Andrey Pronin 2016-07-19 12:55 ` Jarkko Sakkinen 2016-07-19 12:55 ` Jarkko Sakkinen 2016-07-20 0:24 ` Andrey Pronin 2016-07-20 0:24 ` Andrey Pronin 2016-07-20 17:03 ` Jason Gunthorpe 2016-07-20 17:03 ` Jason Gunthorpe 2016-07-21 18:10 ` Andrey Pronin 2016-07-21 18:10 ` Andrey Pronin 2016-07-21 21:00 ` Jason Gunthorpe 2016-07-21 21:00 ` Jason Gunthorpe 2016-07-15 2:28 ` [PATCH 0/2] " Peter Huewe 2016-07-15 2:28 ` Peter Huewe 2016-07-15 2:50 ` Andrey Pronin 2016-07-15 3:28 ` Jason Gunthorpe 2016-07-15 3:28 ` Jason Gunthorpe 2016-07-15 17:15 ` Andrey Pronin 2016-07-15 17:15 ` Andrey Pronin 2016-07-19 12:56 ` Jarkko Sakkinen 2016-07-20 3:41 ` [PATCH v2 " Andrey Pronin 2016-07-20 3:41 ` Andrey Pronin 2016-07-20 3:41 ` [PATCH v2 1/2] tpm: devicetree: document properties for cr50 Andrey Pronin 2016-07-20 3:41 ` Andrey Pronin 2016-07-20 19:03 ` Rob Herring 2016-07-20 19:49 ` Andrey Pronin [this message] 2016-07-20 19:49 ` Andrey Pronin 2016-07-20 19:54 ` Jason Gunthorpe 2016-07-20 19:54 ` Jason Gunthorpe 2016-07-27 21:02 ` Andrey Pronin 2016-07-27 21:02 ` Andrey Pronin 2016-07-21 21:03 ` Rob Herring 2016-07-21 21:03 ` Rob Herring 2016-07-27 21:00 ` Andrey Pronin 2016-07-27 21:00 ` Andrey Pronin 2016-07-20 3:41 ` [PATCH v2 2/2] tpm: add driver for cr50 on SPI Andrey Pronin 2016-07-20 3:41 ` Andrey Pronin 2016-07-25 17:09 ` Aw: [PATCH v2 0/2] " Peter Huewe 2016-07-25 17:09 ` Peter Huewe 2016-07-27 21:12 ` Andrey Pronin 2016-07-28 4:25 ` [PATCH v3 " Andrey Pronin 2016-07-28 4:25 ` Andrey Pronin 2016-07-28 4:25 ` [PATCH v3 1/2] tpm: devicetree: document properties for cr50 Andrey Pronin 2016-07-28 4:25 ` Andrey Pronin 2016-07-28 4:25 ` [PATCH v3 2/2] tpm: add driver for cr50 on SPI Andrey Pronin 2016-07-28 4:25 ` Andrey Pronin 2016-07-28 23:01 ` Dmitry Torokhov 2016-07-28 23:17 ` Jason Gunthorpe 2016-07-28 23:17 ` Jason Gunthorpe 2016-07-29 3:01 ` Andrey Pronin 2016-07-29 3:01 ` Andrey Pronin 2016-07-29 1:55 ` [PATCH v4 0/2] " Andrey Pronin 2016-07-29 1:55 ` Andrey Pronin 2016-07-29 1:55 ` [PATCH v4 1/2] tpm: devicetree: document properties for cr50 Andrey Pronin 2016-07-29 1:55 ` Andrey Pronin 2016-07-29 17:27 ` Jason Gunthorpe 2016-07-29 17:27 ` Jason Gunthorpe 2016-07-29 21:42 ` Rob Herring 2016-07-29 21:42 ` Rob Herring 2016-08-09 10:08 ` Jarkko Sakkinen 2016-08-09 10:08 ` Jarkko Sakkinen 2016-07-29 1:55 ` [PATCH v4 2/2] tpm: add driver for cr50 on SPI Andrey Pronin 2016-07-29 1:55 ` Andrey Pronin 2016-08-09 10:20 ` Jarkko Sakkinen
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