linux-kernel - RE: [PATCH] USB: ehci-pci: USB host controller support for Intel Quark X1000

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Date:	Thu, 26 Jun 2014 01:16:08 +0000
From:	"Chen, Alvin" <alvin.chen@...el.com>
To:	Jingoo Han <jg1.han@...sung.com>
CC:	'Alan Stern' <stern@...land.harvard.edu>,
	'Greg Kroah-Hartman' <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Ong, Boon Leong" <boon.leong.ong@...el.com>
Subject: RE: [PATCH] USB: ehci-pci: USB host controller support for Intel
 Quark X1000

> > This patch is to enable USB host controller for Intel Quark X1000. Add
> > pci quirks to adjust the packet buffer in/out threshold value, and
> > ensure EHCI packet buffer i/o threshold value is reconfigured to half.
> 
> Please add more detailed description. For example, why is it necessary to
> reconfigure the threshold value?
> 
This patch try to reconfigure the threshold value as maximal (0x7F DWord) as possible since the default value is just 0x20 DWord, and I will update the description.

> >
> > +
> > +#define EHCI_INSNREG01		0x84
> > +#define EHCI_INSNREG01_THRESH	0x007F007F	/* Threshold value */
> 
> What does this magic number mean?
> Would you make it more readable?
0x84 is the register offset, and the high word of '0x007F007F' is the out threshold and the low word is the in threshold. I will use some micros to make it more readable to avoid magic number in PATCH v2.



> > +void usb_set_qrk_bulk_thresh(struct pci_dev *pdev) {
> > +	void __iomem *base, *op_reg_base;
> > +	u8 cap_length;
> > +	u32 val;
> > +
> > +	if (!mmio_resource_enabled(pdev, 0))
> > +		return;
> > +
> > +	base = pci_ioremap_bar(pdev, 0);
> > +	if (base == NULL)
> > +		return;
> > +
> > +	cap_length = readb(base);
> > +	op_reg_base = base + cap_length;
> > +
> > +	val = readl(op_reg_base + EHCI_INSNREG01);
> > +	dev_printk(KERN_INFO, &pdev->dev, "INSNREG01 is 0x%08x\n", val);
> > +
> > +	val = EHCI_INSNREG01_THRESH;
> > +
> > +	writel(val, op_reg_base + EHCI_INSNREG01);
> > +
> > +	val = readl(op_reg_base + EHCI_INSNREG01);
> > +	dev_printk(KERN_INFO, &pdev->dev, "INSNREG01 is 0x%08x\n", val);
> 
> As Alan Stern said, These INFO message are noisy.
> DEBUG level looks better.
These messages are not necessary, I will remove them.



> Best regards,
> Jingoo Han
> 
> > +
> > --
> > 1.7.9.5

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