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From: Flavio Suligoi <f.suligoi@asem.it>
To: Mark Brown <broonie@kernel.org>
Cc: Daniel Mack <daniel@zonque.org>,
	Haojian Zhuang <haojian.zhuang@gmail.com>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 2/2] spi: pxa2xx: use a module softdep for dw_dmac
Date: Wed, 10 Apr 2019 14:05:38 +0000	[thread overview]
Message-ID: <6eeaf42f4d3f42c58546c429194213b8@asem.it> (raw)
In-Reply-To: <20190410125612.GR6106@sirena.org.uk>

Hi Mark,

> On Wed, Apr 10, 2019 at 02:51:36PM +0200, Flavio Suligoi wrote:
> > With dw_dmac, sometimes the request of a DMA channel fails because
> > the DMA driver is not ready, so an explicit dependency request
> > is necessary.
> 
> While this isn't going to hurt anything and might actually help so it's
> fine doesn't this also suggest that there's an issue with deferred probe
> going on as well?

I think that the problem could be related to how the DMA channel is requested.
At the moment the function used are:

pxa2xx_spi_dma_setup --> dma_request_slave_channel_compat -->
--> __dma_request_slave_channel_compat --> dma_request_slave_channel -->
--> dma_request_chan

Actually the final function "dma_request_chan" return
the channel number or "-EPROBE_DEFER" if it's not ready.
But this information ("-EPROBE_DEFER") is lost in the penultimate function 
"dma_request_slave_channel", which return only the chann, if all is ok, or
NULL, in case of errors.
So the deferral mechanism is not used.

Flavio

WARNING: multiple messages have this Message-ID (diff)
From: Flavio Suligoi <f.suligoi@asem.it>
To: Mark Brown <broonie@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Haojian Zhuang <haojian.zhuang@gmail.com>,
	"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
	Daniel Mack <daniel@zonque.org>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH 2/2] spi: pxa2xx: use a module softdep for dw_dmac
Date: Wed, 10 Apr 2019 14:05:38 +0000	[thread overview]
Message-ID: <6eeaf42f4d3f42c58546c429194213b8@asem.it> (raw)
In-Reply-To: <20190410125612.GR6106@sirena.org.uk>

Hi Mark,

> On Wed, Apr 10, 2019 at 02:51:36PM +0200, Flavio Suligoi wrote:
> > With dw_dmac, sometimes the request of a DMA channel fails because
> > the DMA driver is not ready, so an explicit dependency request
> > is necessary.
> 
> While this isn't going to hurt anything and might actually help so it's
> fine doesn't this also suggest that there's an issue with deferred probe
> going on as well?

I think that the problem could be related to how the DMA channel is requested.
At the moment the function used are:

pxa2xx_spi_dma_setup --> dma_request_slave_channel_compat -->
--> __dma_request_slave_channel_compat --> dma_request_slave_channel -->
--> dma_request_chan

Actually the final function "dma_request_chan" return
the channel number or "-EPROBE_DEFER" if it's not ready.
But this information ("-EPROBE_DEFER") is lost in the penultimate function 
"dma_request_slave_channel", which return only the chann, if all is ok, or
NULL, in case of errors.
So the deferral mechanism is not used.

Flavio


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

  reply	other threads:[~2019-04-10 14:05 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-10 12:51 [PATCH 1/2] spi: pxa2xx: fix SCR (divisor) calculation Flavio Suligoi
2019-04-10 12:51 ` Flavio Suligoi
2019-04-10 12:51 ` [PATCH 2/2] spi: pxa2xx: use a module softdep for dw_dmac Flavio Suligoi
2019-04-10 12:51   ` Flavio Suligoi
2019-04-10 12:56   ` Mark Brown
2019-04-10 12:56     ` Mark Brown
2019-04-10 14:05     ` Flavio Suligoi [this message]
2019-04-10 14:05       ` Flavio Suligoi
2019-04-10 15:28       ` Mark Brown
2019-04-10 15:28         ` Mark Brown
2019-04-11  7:14         ` Flavio Suligoi
2019-04-11  7:14           ` Flavio Suligoi
2019-04-11 10:42           ` Mark Brown
2019-04-11 10:42             ` Mark Brown
2019-04-11 11:31             ` Flavio Suligoi
2019-04-11 11:31               ` Flavio Suligoi
2019-04-12  8:53   ` Applied "spi: pxa2xx: use a module softdep for dw_dmac" to the spi tree Mark Brown
2019-04-12  8:53     ` Mark Brown
2019-04-12  8:53     ` Mark Brown
2019-05-02  2:19   ` Mark Brown
2019-05-02  2:19     ` Mark Brown
2019-05-02  2:19     ` Mark Brown
2019-04-11 11:55 ` [PATCH 1/2] spi: pxa2xx: fix SCR (divisor) calculation Jarkko Nikula
2019-04-11 11:55   ` Jarkko Nikula
2019-04-11 13:10   ` Flavio Suligoi
2019-04-11 13:10     ` Flavio Suligoi

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