On Friday, June 27, 2014 1:33 PM, Jingoo Han wrote:
> On Friday, June 27, 2014 8:25 PM, Alvin Chen wrote:
> >
> > From: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxx>
> >
> > The EHCI packet buffer in/out threshold is programmable for Intel Quark X1000 USB host
> > controller, and the default value is 0x20 dwords. The in/out threshold can be programmed
> > to 0x80 dwords, but only when isochronous/interrupt transactions are not initiated by
> > the USB host controller. This patch is to reconfigure the packet buffer in/out threshold
> > as maximal as possible, and it is 0x7F dwords since the USB host controller initiates
> > isochronous/interrupt transactions.
>
> So, what is the reason to set the value as 0x80?
> 1. The default value 0x20 makes some problems such as...
> 2. To maximize the performance, ...
> 3. Both
> Please add the reason why 0x80 is necessary, as possible.
>
> Then, 0x7F means 508 bytes? 'Intel Quark X1000 USB host controller'
> can support 0x80 (512bytes), however, in this case, isochronous/interrupt
> transactions cannot be initiated by 'Intel Quark X1000 USB host controller'.
> Right?
>
> So, 0x79 (508bytes?) should be used, because the isochronous/interrupt
> transactions can be initiated by 'Intel Quark X1000 USB host controller'.
> Right?
>
> >
> > Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxx>
> > Signed-off-by: Alvin (Weike) Chen <alvin.chen@xxxxxxxxx>
> > ---
> > changelog v2:
> > *Change the function name from 'usb_is_intel_qrk' to 'usb_is_intel_quark_x1000'.
> > *Move the functions 'usb_is_intel_quark_x1000' and 'usb_set_qrk_bulk_thresh'
> > from 'pci-quirks.c' to 'ehci-pci.c'.
> > *Remove unnecessary kernel message in the function of 'usb_set_qrk_bulk_thresh'.
> > *Remove 'unlikely' in the functions of 'ehci_pci_reinit'.
> > *Add white space after 'if'.
> > *Update the descriptions to make it more clearly.
> > *Add Micros to avoid magic number.
> >
> > drivers/usb/host/ehci-pci.c | 45 +++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 45 insertions(+)
> >
> > diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
> > index 3e86bf4..ca29f34 100644
> > --- a/drivers/usb/host/ehci-pci.c
> > +++ b/drivers/usb/host/ehci-pci.c
> > @@ -35,6 +35,47 @@ static const char hcd_name[] = "ehci-pci";
> > #define PCI_DEVICE_ID_INTEL_CE4100_USB 0x2e70
> >
> > /*-------------------------------------------------------------------------*/
> > +#define PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC 0x0939
> > +static inline bool usb_is_intel_quark_x1000(struct pci_dev *pdev)
> > +{
> > + return pdev->vendor == PCI_VENDOR_ID_INTEL &&
> > + pdev->device == PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC;
> > +
>
> Please don't add this unnecessary line.
>
> > +}
> > +
> > +/* Register offset of in/out threshold */
> > +#define EHCI_INSNREG01 0x84
> > +/* The maximal threshold is 0x80 Dword */
> > +#define EHCI_MAX_THRESHOLD 0X80
>
> s/0X80/0x80
>
> 0x80 means 512 bytes. So, how about mentioning '0x80 means 512 bytes'
> in this comment or the commit message?
>
> Maybe, how about the following?
>
> /* The maximal threshold value is 0x80, which means 512 bytes */
> #define EHCI_THRESHOLD_512BYTES 0x80
>
> > +/* Lower word is 'in' threshold, and higher word is 'out' threshold*/
> > +#define EHCI_INSNREG01_THRESH \
> > + ((EHCI_MAX_THRESHOLD - 1)<<16 | (EHCI_MAX_THRESHOLD - 1))
>
> Um, how about the following?
>
> /* Register offset of in/out threshold */
> #define EHCI_INSNREG01 0x84
> /* The maximal threshold value is 0x80, which means 512 bytes */
> #define EHCI_THRESHOLD_512BYTES 0x80
> #define EHCI_THRESHOLD_508BYTES 0x79
> #define EHCI_THRESHOLD_OUT_SHIFT 16
> #define EHCI_THRESHOLD_IN_SHIFT 0
>
> ......
>
> /*
> * In order to support the isochronous/interrupt transactions,
> * 508 bytes should be used as max threshold values */
> */
> val = ((EHCI_THRESHOLD_512BYTES - 1) << EHCI_THRESHOLD_OUT_SHIFT |
> (EHCI_THRESHOLD_512BYTES - 1) << EHCI_THRESHOLD_IN_SHIFT);
> writel(val, op_reg_base + EHCI_INSNREG01);
Sorry, please refer to the following.
/* Register offset of in/out threshold */
#define EHCI_INSNREG01 0x84
/* The maximal threshold value is 0x80, which means 512 bytes */
#define EHCI_THRESHOLD_512BYTES 0x80
#define EHCI_THRESHOLD_508BYTES 0x79
#define EHCI_THRESHOLD_OUT_SHIFT 16
#define EHCI_THRESHOLD_IN_SHIFT 0
......
/*
* In order to support the isochronous/interrupt transactions,
* 508 bytes should be used as max threshold values */
*/
val = (EHCI_THRESHOLD_508BYTES << EHCI_THRESHOLD_OUT_SHIFT |
(EHCI_THRESHOLD_508BYTES << EHCI_THRESHOLD_IN_SHIFT);
writel(val, op_reg_base + EHCI_INSNREG01);
>
>
> > +static void usb_set_qrk_bulk_thresh(struct pci_dev *pdev)
>
> Please, use usb_set_qrk_bulk_threshold().
> The 'threshold' looks better than 'thresh'.
>
> > +{
> > + void __iomem *base, *op_reg_base;
> > + u8 cap_length;
> > + u32 val;
> > + u16 cmd;
> > +
> > + if (!pci_resource_start(pdev, 0))
> > + return;
> > +
> > + if (pci_read_config_word(pdev, PCI_COMMAND, &cmd)
> > + || !(cmd & PCI_COMMAND_MEMORY))
> > + return;
> > +
> > + base = pci_ioremap_bar(pdev, 0);
> > + if (base == NULL)
> > + return;
> > +
> > + cap_length = readb(base);
> > + op_reg_base = base + cap_length;
> > +
> > + val = EHCI_INSNREG01_THRESH;
> > + writel(val, op_reg_base + EHCI_INSNREG01);
> > +
> > + iounmap(base);
> > +}
> >
> > /* called after powerup, by probe or system-pm "wakeup" */
> > static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
> > @@ -50,6 +91,10 @@ 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 (usb_is_intel_quark_x1000(pdev))
> > + usb_set_qrk_bulk_thresh(pdev);
> > +
> > return 0;
> > }
> >
> > --
> > 1.7.9.5
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