Re: [V2 PATCH 02/10] added media agnostic (MA) USB HCD roothubs

Sean O. Stalley
2014-11-12T19:28:34Z

Thank you for your review. My responses are inline.

Greg has requested that we clean up the driver internally before
we resubmit another patchset to the mailing list. I will make
sure the changes you requested make it in, but it may be a while
before you see a patchset with the fixes included.

Thanks,
Sean O. Stalley

On Wed, Nov 12, 2014 at 09:35:42AM +0100, Oliver Neukum wrote:
> On Mon, 2014-11-10 at 18:09 -0800, Stephanie Wallick wrote:
> > diff --git a/drivers/staging/mausb/drivers/mausb_hub.c b/drivers/staging/mausb/drivers/mausb_hub.c
> > new file mode 100644
> > index 0000000..63c0fe4
> > --- /dev/null
> > +++ b/drivers/staging/mausb/drivers/mausb_hub.c
>
> > +/**
> > + * Returns true if the given is the superspeed HCD. Note: The primary HCD is
> > + * High Speed and the shared HCD is SuperSpeed.
> > + */
>
> Why in that order?
>

We should probably switch this & make the superspeed hub primary.
That way we match the xhci driver.

> > +bool mausb_is_ss_hcd(struct usb_hcd *hcd)
> > +{
> > + if (usb_hcd_is_primary_hcd(hcd))
> > + return false;
> > + else
> > + return true;
> > +}
>
>
>
> > +
> > +/**
> > + * Called by usb core when polling for a port status change.
> > + *
> > + * @hcd: USB HCD being polled.
> > + * @buf: Holds port status changes (if any).
> > + *
> > + * Returns zero if there is no status change, otherwise returns number of
> > + * bytes in buf. When there is a status change on a port, the bit indexed
> > + * at the port number + 1 (e.g. bit 2 for port 1) is set in the buffer.
> > + */
> > +int mausb_hub_status_data(struct usb_hcd *hcd, char *buf)
> > +{
> > + int i;
> > + u16 port_change = 0;
> > + u32 status = 0;
> > + int ret = 1;
> > + struct mausb_hcd *mhcd = usb_hcd_to_mausb_hcd(hcd);
> > + struct mausb_root_hub *roothub = usb_hcd_to_roothub(hcd);
> > +
> > + /*
> > + * Buf should never be more that 2 bytes. USB 3.0 hubs cannot have
> > + * more than 15 downstream ports.
> > + */
> > + buf[0] = 0;
> > + if (MAUSB_ROOTHUB_NUM_PORTS > 7) {
> > + buf[1] = 0;
> > + ret++;
> > + }
>
> Endianness bug.
>

Could you elaborate?
It was my understanding that this buffer was host-endian.
Is this an unacceptable way to clear the buffer?

> > +
> > + for (i = 0; i < MAUSB_ROOTHUB_NUM_PORTS; i++) {
> > + port_change = roothub->port_status[i].wPortChange;
> > + if (port_change)
> > + status |= (1 << (i + 1));
> > + }
> > +
> > + mausb_dbg(mhcd, "%s: hub status is 0x%x\n", __func__, status);
> > +
> > + /* hcd might be suspended, resume if there is a status change */
> > + if (mhcd->disabled == 0) {
> > + if ((hcd->state == HC_STATE_SUSPENDED) && status)
> > + usb_hcd_resume_root_hub(hcd);
> > + }
> > +
> > + memcpy(buf, (char *)&status, ret);
> > +
> > + return status ? ret : 0;
> > +}
> > +
> > +/**
> > + * Sets the bitfields in the hub descriptor of the 2.0 root hub. Always
> > + * returns zero.
> > + */
> > +int mausb_set_hub_descriptor(struct usb_hub_descriptor *hub_des)
> > +{
> > + /* set the values to the default */
> > + hub_des->bDescLength = sizeof(struct usb_hub_descriptor);
> > + hub_des->bDescriptorType = USB_DT_HUB;
> > + hub_des->bNbrPorts = MAUSB_ROOTHUB_NUM_PORTS;
> > + hub_des->wHubCharacteristics = MAUSB_ROOTHUB_CHAR;
> > + hub_des->bPwrOn2PwrGood = MAUSB_ROOTHUB_PWR_ON_2_PWR_GOOD;
> > + hub_des->bHubContrCurrent = MAUSB_ROOTHUB_CONTR_CURRENT;
>
> Is that descriptor in bus or host endianness?
>

All of the fields are little-endian. We should be using cpu_to_le16()
when setting wHubCharacteristics.

> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * Sets the bitfields in the hub descriptor of the 3.0 root hub. Always
> > + * returns zero.
>
> Then why return anything?
>

Good point. I will change this (and mausb_set_hub_descriptor()) to be void.

> > + */
> > +int mausb_set_ss_hub_descriptor(struct usb_hub_descriptor *hub_des)
> > +{
> > + /* set the values to the default */
> > + hub_des->bDescLength = sizeof(struct usb_hub_descriptor);
> > + hub_des->bDescriptorType = USB_DT_SS_HUB;
> > + hub_des->bNbrPorts = MAUSB_ROOTHUB_NUM_PORTS;
> > + hub_des->wHubCharacteristics = MAUSB_ROOTHUB_CHAR;
> > + hub_des->bPwrOn2PwrGood = MAUSB_ROOTHUB_PWR_ON_2_PWR_GOOD;
> > + hub_des->bHubContrCurrent = MAUSB_ROOTHUB_CONTR_CURRENT;
> > +
> > + /* USB3-specific parameters */
> > + hub_des->u.ss.bHubHdrDecLat = MAUSB_ROOTHUB_HDR_DEC_LAT;
> > + hub_des->u.ss.wHubDelay = MAUSB_ROOTHUB_DELAY;
> > + hub_des->u.ss.DeviceRemovable = MAUSB_ALL_DEV_REMOVABLE;
> > +
> > + return 0;
> > +}
>
>
> > +/**
> > + * Contains all the structures required to emulate a root hub. One instance
> > + * exists per root hub.
> > + */
> > +struct __attribute__((__packed__)) mausb_root_hub {
>
> Why __packed__ ?

Doesn't need to be. I will remove.

> > +
> > + /* hub parameters */
> > + struct usb_hub_descriptor descriptor;
> > + struct usb_hub_status status;
> > +
> > + /* port parameters*/
> > + struct usb_port_status port_status[MAUSB_ROOTHUB_NUM_PORTS];
> > +
> > + /* root hub state */
> > + enum mausb_rh_state rh_state;
> > +
> > +};
>
> HTH
> Oliver
>
> --
> Oliver Neukum <oneukum@suse.de>
>