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From: luhua xu <luhua.xu@mediatek.com>
To: Mark Brown <broonie@kernel.org>
Cc: wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org,
	linux-spi@vger.kernel.org, linux-mediatek@lists.infradead.org,
	Matthias Brugger <matthias.bgg@gmail.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] spi: mediatek: add power control when set_cs
Date: Thu, 24 Oct 2019 14:25:19 +0800	[thread overview]
Message-ID: <1571898319.4311.3.camel@mbjsdccf07> (raw)
In-Reply-To: <20191023151121.GC5723@sirena.co.uk>

On Wed, 2019-10-23 at 16:11 +0100, Mark Brown wrote:
> On Wed, Oct 23, 2019 at 08:38:42AM -0400, Luhua Xu wrote:
> > From: "luhua.xu" <luhua.xu@mediatek.com>
> 
> > Use runtime PM to power spi when set_cs
> > As set_cs may be called from interrupt context,
> > set runtime PM IRQ safe for spi.
> 
> Why might we be trying to set the chip select state while the device is
> runtime idle?  It seems like whatever is trying to set the chip select
> should be dealing with this, not the chip select operation itself since
> that's unlikely to be happening in isolation.

Hi Mark,
Spi framework provideds  spi_setup() to modify spi settings for spi
device (maybe spi is runtime idle now), and this will call
spi_controller->set_cs() accessing registers.
Other spi_controller callbacks that need to access hardware registers,
are triggered by spi transfer. Spi framework will get and put runtime
power in __spi_pump_message().


_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

WARNING: multiple messages have this Message-ID (diff)
From: luhua xu <luhua.xu@mediatek.com>
To: Mark Brown <broonie@kernel.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
	<linux-spi@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <wsd_upstream@mediatek.com>
Subject: Re: [PATCH 1/1] spi: mediatek: add power control when set_cs
Date: Thu, 24 Oct 2019 14:25:19 +0800	[thread overview]
Message-ID: <1571898319.4311.3.camel@mbjsdccf07> (raw)
In-Reply-To: <20191023151121.GC5723@sirena.co.uk>

On Wed, 2019-10-23 at 16:11 +0100, Mark Brown wrote:
> On Wed, Oct 23, 2019 at 08:38:42AM -0400, Luhua Xu wrote:
> > From: "luhua.xu" <luhua.xu@mediatek.com>
> 
> > Use runtime PM to power spi when set_cs
> > As set_cs may be called from interrupt context,
> > set runtime PM IRQ safe for spi.
> 
> Why might we be trying to set the chip select state while the device is
> runtime idle?  It seems like whatever is trying to set the chip select
> should be dealing with this, not the chip select operation itself since
> that's unlikely to be happening in isolation.

Hi Mark,
Spi framework provideds  spi_setup() to modify spi settings for spi
device (maybe spi is runtime idle now), and this will call
spi_controller->set_cs() accessing registers.
Other spi_controller callbacks that need to access hardware registers,
are triggered by spi transfer. Spi framework will get and put runtime
power in __spi_pump_message().

WARNING: multiple messages have this Message-ID (diff)
From: luhua xu <luhua.xu@mediatek.com>
To: Mark Brown <broonie@kernel.org>
Cc: wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org,
	linux-spi@vger.kernel.org, linux-mediatek@lists.infradead.org,
	Matthias Brugger <matthias.bgg@gmail.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] spi: mediatek: add power control when set_cs
Date: Thu, 24 Oct 2019 14:25:19 +0800	[thread overview]
Message-ID: <1571898319.4311.3.camel@mbjsdccf07> (raw)
In-Reply-To: <20191023151121.GC5723@sirena.co.uk>

On Wed, 2019-10-23 at 16:11 +0100, Mark Brown wrote:
> On Wed, Oct 23, 2019 at 08:38:42AM -0400, Luhua Xu wrote:
> > From: "luhua.xu" <luhua.xu@mediatek.com>
> 
> > Use runtime PM to power spi when set_cs
> > As set_cs may be called from interrupt context,
> > set runtime PM IRQ safe for spi.
> 
> Why might we be trying to set the chip select state while the device is
> runtime idle?  It seems like whatever is trying to set the chip select
> should be dealing with this, not the chip select operation itself since
> that's unlikely to be happening in isolation.

Hi Mark,
Spi framework provideds  spi_setup() to modify spi settings for spi
device (maybe spi is runtime idle now), and this will call
spi_controller->set_cs() accessing registers.
Other spi_controller callbacks that need to access hardware registers,
are triggered by spi transfer. Spi framework will get and put runtime
power in __spi_pump_message().


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-10-24  6:25 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-23 12:38 [PATCH 0/1] Add spi power control when set cs Luhua Xu
2019-10-23 12:38 ` Luhua Xu
2019-10-23 12:38 ` Luhua Xu
2019-10-23 12:38 ` [PATCH 1/1] spi: mediatek: add power control when set_cs Luhua Xu
2019-10-23 12:38   ` Luhua Xu
2019-10-23 12:38   ` Luhua Xu
2019-10-23 12:38   ` Luhua Xu
2019-10-23 15:11   ` Mark Brown
2019-10-23 15:11     ` Mark Brown
2019-10-23 15:11     ` Mark Brown
2019-10-24  6:25     ` luhua xu [this message]
2019-10-24  6:25       ` luhua xu
2019-10-24  6:25       ` luhua xu
2019-10-24 10:11       ` luhua xu
2019-10-24 10:11         ` luhua xu
2019-10-24 10:11         ` luhua xu
2019-10-24 11:19         ` Mark Brown
2019-10-24 11:19           ` Mark Brown
2019-10-24 11:19           ` Mark Brown
2019-10-24 10:23       ` Mark Brown
2019-10-24 10:23         ` Mark Brown
2019-10-24 10:23         ` Mark Brown
2019-10-23 15:11 ` [PATCH 0/1] Add spi power control when set cs Mark Brown
2019-10-23 15:11   ` Mark Brown
2019-10-23 15:11   ` Mark Brown

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