Messages in this thread | | | Subject | Re: [RFC 1/5] usb: chipidea: Add support for Tegra20/30/114/124 | From | Stephen Warren <> | Date | Thu, 26 May 2016 15:22:23 -0600 |
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On 05/26/2016 03:17 PM, Stephen Warren wrote: > On 05/26/2016 09:40 AM, Thierry Reding wrote: >> From: Thierry Reding <treding@nvidia.com> >> >> All of these Tegra SoC generations have a ChipIdea UDC IP block that can >> be used for device mode communication with a host. Implement rudimentary >> support that doesn't allow switching between host and device modes. > > Are you sure this is correct for Tegra20? I ask because for the /host/ > mode driver, there's a "has_hostpc" flag which is set to false for > Tegra20 and true for all other SoCs. In the U-Boot device mode driver > (if not in the kernel driver; I didn't check), there's a concept of "has > hostpc" too. I might expect that flag to be set the same way for both > drivers. That said, I /think/ the host and device HW are unrelated, so > it's possible has_hostpc might be set differently for them. > Unfortunately, we haven't enabled the device mode driver for any Tegra20 > system in U-Boot so I can't tell whether we should enable has_hostpc for > Tegra20's device mode driver. > > Still, if this code works then I guess it's likely correct...
On the other hand, it looks like the kernel device mode driver might auto-detect this; in core.c:hw_device_init(), I see:
reg = hw_read(ci, CAP_HCCPARAMS, HCCPARAMS_LEN) >> __ffs(HCCPARAMS_LEN); ci->hw_bank.lpm = reg;
... and in host.c:host_start(), I see:
ehci->has_hostpc = ci->hw_bank.lpm;
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