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

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Date:	Wed, 25 Jun 2014 10:10:43 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	"'Chen, Alvin'" <alvin.chen@...el.com>
Cc:	'Alan Stern' <stern@...land.harvard.edu>,
	'Greg Kroah-Hartman' <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	'Boon Leong Ong' <boon.leong.ong@...el.com>,
	'Jingoo Han' <jg1.han@...sung.com>
Subject: Re: [PATCH] USB: ehci-pci: USB host controller support for Intel Quark
 X1000

On Wednesday, June 25, 2014 12:52 AM, Alvin Chen wrote:
> 
> From: Bryan O'Donoghue <bryan.odonoghue@...el.com>
> 
> 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?

> 
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...el.com>
> Signed-off-by: Alvin (Weike) Chen <alvin.chen@...el.com>
> ---
>  drivers/usb/host/ehci-pci.c   |    4 ++++
>  drivers/usb/host/pci-quirks.c |   42 +++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/host/pci-quirks.h |    2 ++
>  3 files changed, 48 insertions(+)
> 
> diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
> index 3e86bf4..33cfa23 100644
> --- a/drivers/usb/host/ehci-pci.c
> +++ b/drivers/usb/host/ehci-pci.c
> @@ -50,6 +50,10 @@ static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
>  	if (!retval)
>  		ehci_dbg(ehci, "MWI active\n");
> 
> +	/* Reset the threshold limit */
> +	if(unlikely(usb_is_intel_qrk(pdev)))
> +		usb_set_qrk_bulk_thresh(pdev);
> +
>  	return 0;
>  }
> 
> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index 00661d3..1ea8803 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c
> @@ -823,6 +823,48 @@ static int handshake(void __iomem *ptr, u32 mask, u32 done,
>  	return -ETIMEDOUT;
>  }
> 
> +#define PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC		0x0939
> +bool usb_is_intel_qrk(struct pci_dev *pdev)
> +{
> +	return pdev->vendor == PCI_VENDOR_ID_INTEL &&
> +		pdev->device == PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC;
> +
> +}
> +EXPORT_SYMBOL_GPL(usb_is_intel_qrk);
> +
> +#define EHCI_INSNREG01		0x84
> +#define EHCI_INSNREG01_THRESH	0x007F007F	/* Threshold value */

What does this magic number mean?
Would you make it more readable?

> +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.

Best regards,
Jingoo Han

> +
> +	iounmap(base);
> +
> +}
> +EXPORT_SYMBOL_GPL(usb_set_qrk_bulk_thresh);
> +
>  /*
>   * Intel's Panther Point chipset has two host controllers (EHCI and xHCI) that
>   * share some number of ports.  These ports can be switched between either
> diff --git a/drivers/usb/host/pci-quirks.h b/drivers/usb/host/pci-quirks.h
> index c622ddf..617c22b 100644
> --- a/drivers/usb/host/pci-quirks.h
> +++ b/drivers/usb/host/pci-quirks.h
> @@ -14,6 +14,8 @@ void usb_amd_quirk_pll_enable(void);
>  void usb_enable_intel_xhci_ports(struct pci_dev *xhci_pdev);
>  void usb_disable_xhci_ports(struct pci_dev *xhci_pdev);
>  void sb800_prefetch(struct device *dev, int on);
> +bool usb_is_intel_qrk(struct pci_dev *pdev);
> +void usb_set_qrk_bulk_thresh(struct pci_dev *pdev);
>  #else
>  struct pci_dev;
>  static inline void usb_amd_quirk_pll_disable(void) {}
> --
> 1.7.9.5

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