From mboxrd@z Thu Jan  1 00:00:00 1970
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Thu, 03 Oct 2013 09:47:04 +0000
Subject: Re: [PATCH 2/6] arm: shmobile: lager: Add USBHS support
Message-Id: <6394987.Uanypf6pjs@avalon>
List-Id: <linux-sh.vger.kernel.org>
References: <1380652251-8143-3-git-send-email-valentine.barshak@cogentembedded.com>
In-Reply-To: <1380652251-8143-3-git-send-email-valentine.barshak@cogentembedded.com>
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To: linux-sh@vger.kernel.org

Hi Morimoto-san,

On Wednesday 02 October 2013 21:53:26 Kuninori Morimoto wrote:
> Hi Valentine
> 
> > >> +static int usbhs_hardware_init(struct platform_device *pdev)
> > >> +{
> > >> +	struct usbhs_private *priv = usbhs_get_priv(pdev);
> > >> +	struct clk *clk;
> > >> +
> > >> +	clk = clk_get(NULL, "hsusb");
> > >> +	if (IS_ERR(clk))
> > >> +		return -ENODEV;
> > > 
> > > It is automatically enable/disabled by driver
> > > if MSTP704 clock name was "renesas_usbhs".
> > 
> > The reason I did not bind usbhs clock to renesas_usbhs device is because
> > the same clock is also used by the lager_add_usb_devices() function in
> > the next patches. We need that since the global USB settings that affect
> > USBHS/USBSS and PCI USB host channel sharing are done in the USBHS
> > UGCTRL2 register. So we need this clock even if the renesas_usbhs driver
> > is disabled. IIUC, biding it to "renesas_usbhs" device would make it
> > impossible to use the clock if renesas_usbhs device is not registered.
> 
> I understand your situation, but you can use renesas_usbhs binded clock
> anyway ? As Laurent mentioned, pci-rcar-gen2 care about it in driver ?
> Maybe callback function is nice solution in this situation ?
> Like this
> 
> --- clock --------------
>   CLKDEV_DEV_ID("renesas_usbhs", &mstp_clks[MSTP704]),
>   CLKDEV_ICK_ID("hsusb", "pci-rcar-gen2", &mstp_clks[MSTP704]),
> 
> --- platform -----------
> int rcar_pci_hw_init(struct platform_device *pdev)
> {
>         clk = clk_get("hsusb", pdev->dev);
>         if (IS_ERR(clk))
>                  return -EIO;
> 
>         clk_enable(clk);
>         clk_put(clk);
> 
>         ...
> 
>         return 0;
> }
> 
> --- driver ---
> static int __init rcar_pci_probe(struct platform_device *pdev)
> {
>         ...
>         if (info->hw_init)
>              ret = info->hw_init(pdev);
>         ...
> }

The problem with such a mechanism is that it only works with platform data, as 
we don't have callback functions in DT.

-- 
Regards,

Laurent Pinchart