Re: [PATCH 2/2] mfd: anatop: permit adata be NULL when access register

From: Richard Zhao <richard.zhao@freescale.com>
To: "Ying-Chun Liu (PaulLiu)" <paul.liu@linaro.org>
Cc: <sameo@linux.intel.com>,
	Mark Brown <broonie@opensource.wolfsonmicro.com>,
	<linux-kernel@vger.kernel.org>,
	Shawn Guo <shawn.guo@freescale.com>, <shawn.guo@linaro.org>,
	Richard Zhao <richard.zhao@linaro.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/2] mfd: anatop: permit adata be NULL when access register
Date: Fri, 18 May 2012 17:59:32 +0800	[thread overview]
Message-ID: <20120518095932.GI30755@b20223-02.ap.freescale.net> (raw)
In-Reply-To: <20120514135035.GC29393@b20223-02.ap.freescale.net>

On Mon, May 14, 2012 at 09:50:36PM +0800, Richard Zhao wrote:
> On Mon, May 14, 2012 at 09:26:57PM +0800, Ying-Chun Liu (PaulLiu) wrote:
> > (2012年05月14日 17:43), Shawn Guo wrote:
> > > On Mon, May 14, 2012 at 05:01:08PM +0800, Ying-Chun Liu (PaulLiu) wrote:
> > >> I think what the concern is we probably don't want several
> > >> non-continuous memory blocks of misc hardwares.
> > >> If we look into the current registers in anatop, it is really sparse.
> > >> Several regulators are using non-continuous address and the thermals are
> > >> also using different addresses. If the addresses are continuous then we
> > >> don't need the mfd driver.
> > >>
> > > I do not quite follow that.  The reason we need mfd driver isn't because
> > > we do not want to both regulator and thermal drivers to map and access
> > > the same address on their own which may have synchronization issue?
> > > 
> > 
> > Not sure about the synchronization issue. But currently thermal driver
> > in Linaro kernel do map and access the same address on its own now. It
> > is not a device driver yet and just access the address directly and
> > work. It seems to me that each different type of misc devices in Anatop
> > just work alone.
Guys, we need to draw conclusion.
I think current patch keep some how compatible with multi-anatop.
It's ok.

Thanks
Richard
> > 
> > So let's go back to the patch. Why do we need this modification? Anatop
> > thermal driver can be written as a device driver and don't need this
> > patch. And we might get benefits when thermal driver written in this
> > way. Especially some boards do not have a correct fuse data. Any real
> > use cases of this patch?
> Some bits in anatop is not owned by any driver.
> It's for below code:
>         /* Some phy and power's special controls for host1           
>          * 1. The external charger detector needs to be disabled
>          * or the signal at DP will be poor                          
>          * 2. The PLL's power and output to usb for host 1
>          * is totally controlled by IC, so the Software only needs   
>          * to enable them at initializtion.
>          */ 
>         
>         anatop_write_reg(NULL, HW_ANADIG_USB2_CHRG_DETECT,           
>                         BM_ANADIG_USB2_CHRG_DETECT_EN_B |
>                         BM_ANADIG_USB2_CHRG_DETECT_CHK_CHRG_B,       
>                         ~0);
>         anatop_write_reg(NULL, HW_ANADIG_USB2_PLL_480_CTRL, 0,       
>                         BM_ANADIG_USB2_PLL_480_CTRL_BYPASS);
> 
>         val = BM_ANADIG_USB2_PLL_480_CTRL_ENABLE |                   
>               BM_ANADIG_USB2_PLL_480_CTRL_POWER |
>               BM_ANADIG_USB2_PLL_480_CTRL_EN_USB_CLKS;               
>         anatop_write_reg(NULL, HW_ANADIG_USB2_PLL_480_CTRL, val, val);
> 
> Thanks
> Richard
> > 
> > Yours Sincerely,
> > Paul
> > 
> 
> 
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