Linux SPI subsystem development
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From: Stephan Olbrich <stephanolbrich-Mmb7MZpHnFY@public.gmane.org>
To: linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Cc: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Eric Anholt <eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org>,
	linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 3/4] spi: bcm2835aux: set up spi-mode before asserting cs-gpio
Date: Wed, 10 Feb 2016 21:26:05 +0100	[thread overview]
Message-ID: <2743238.b2UJKq0efN@chaos-desktop> (raw)
In-Reply-To: <20160210190204.GD13270-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>

Am Wednesday 10 February 2016, 19:02:04 schrieb Mark Brown:
> On Wed, Feb 10, 2016 at 10:59:29AM -0800, Eric Anholt wrote:
> > Oops, this makes more sense now.  Subject even mentioned gpio, and a
> > GPIO CS must be getting set around the transfer_one call.  I'll be ready
> > to send an r-b for a v2 with the speed update bug fixed (unless transfer
> > speeds are guaranteed to be constant between a prepare and unprepare).
> 
> No guarantee that they'll not change, especially in a situation where we
> have two devices on different speeds on a bus working at the same time.
Are you saying, that between a prepare and unprepare there could be transfers 
for another device? Then all the clock setting couldn't be done in prepare 
either.
Apart from that, if two transfers in the same message are not guarantied to 
have the same speed, this still needs to be fixed. I'll roll a v2.
--
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  parent reply	other threads:[~2016-02-10 20:26 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-09 18:10 [PATCH 0/4] spi: bcm2835aux: auxiliary spi improvements stephanolbrich-Mmb7MZpHnFY
     [not found] ` <1455041435-8015-1-git-send-email-stephanolbrich-Mmb7MZpHnFY@public.gmane.org>
2016-02-09 18:10   ` [PATCH 1/4] spi: bcm2835aux: fix bitmask defines stephanolbrich-Mmb7MZpHnFY
     [not found]     ` <1455041435-8015-2-git-send-email-stephanolbrich-Mmb7MZpHnFY@public.gmane.org>
2016-02-09 19:54       ` Stefan Wahren
     [not found]         ` <56BA43DB.7030209-saaNCTdWVBT7BZbvpMY5sg@public.gmane.org>
2016-02-10 20:08           ` Stephan Olbrich
2016-02-09 23:44       ` Eric Anholt
2016-02-10 12:55       ` Applied "spi: bcm2835aux: fix bitmask defines" to the spi tree Mark Brown
2016-02-09 18:10   ` [PATCH 2/4] spi: bcm2835aux: disable tx fifo empty irq stephanolbrich-Mmb7MZpHnFY
     [not found]     ` <1455041435-8015-3-git-send-email-stephanolbrich-Mmb7MZpHnFY@public.gmane.org>
2016-02-09 23:45       ` Eric Anholt
2016-02-10 19:22       ` Applied "spi: bcm2835aux: disable tx fifo empty irq" to the spi tree Mark Brown
2016-02-09 18:10   ` [PATCH 3/4] spi: bcm2835aux: set up spi-mode before asserting cs-gpio stephanolbrich-Mmb7MZpHnFY
     [not found]     ` <1455041435-8015-4-git-send-email-stephanolbrich-Mmb7MZpHnFY@public.gmane.org>
2016-02-09 23:49       ` Eric Anholt
     [not found]         ` <87d1s54f7f.fsf-omZaPlIz5HhaEpDpdNBo/KxOck334EZe@public.gmane.org>
2016-02-10  8:01           ` Mark Brown
     [not found]             ` <20160210080149.GQ13270-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-02-10 18:59               ` Eric Anholt
     [not found]                 ` <878u2s2xym.fsf-omZaPlIz5HhaEpDpdNBo/KxOck334EZe@public.gmane.org>
2016-02-10 19:02                   ` Mark Brown
     [not found]                     ` <20160210190204.GD13270-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-02-10 20:26                       ` Stephan Olbrich [this message]
2016-02-10 23:19                         ` Martin Sperl
2016-02-11 12:27                         ` Mark Brown
2016-02-11 18:06       ` Martin Sperl
2016-02-09 18:10   ` [PATCH 4/4] spi: bcm2835aux: fix CPOL/CPHA setting stephanolbrich-Mmb7MZpHnFY
     [not found]     ` <1455041435-8015-5-git-send-email-stephanolbrich-Mmb7MZpHnFY@public.gmane.org>
2016-02-09 20:21       ` Stefan Wahren
2016-02-10  0:13       ` Eric Anholt
     [not found]         ` <87a8n94e3x.fsf-omZaPlIz5HhaEpDpdNBo/KxOck334EZe@public.gmane.org>
2016-02-10 20:45           ` Stephan Olbrich
2016-02-10 21:24             ` Eric Anholt
2016-02-11 15:25           ` Martin Sperl
     [not found]             ` <16A848EA-6E08-48C4-B3DD-DF27333B7458-d5rIkyn9cnPYtjvyW6yDsg@public.gmane.org>
2016-02-11 16:05               ` Stephan Olbrich
2016-02-11 16:19                 ` Martin Sperl
     [not found]                   ` <50D0ECA7-8116-4248-AC85-6E1C8002A185-d5rIkyn9cnPYtjvyW6yDsg@public.gmane.org>
2016-02-11 18:44                     ` Martin Sperl

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