Am Mittwoch, den 23.01.2013, 12:25 +0530 schrieb Venu Byravarasu: > > -----Original Message----- > > From: linux-tegra-owner@xxxxxxxxxxxxxxx [mailto:linux-tegra- > > owner@xxxxxxxxxxxxxxx] On Behalf Of Stephen Warren > > Sent: Wednesday, January 23, 2013 5:58 AM > > To: Alan Stern; Greg Kroah-Hartman; Stephen Warren > > Cc: Venu Byravarasu; linux-tegra@xxxxxxxxxxxxxxx; linux-arm- > > kernel@xxxxxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; Stephen Warren > > Subject: [PATCH 1/2] usb: host: tegra: don't touch EMC clock > > > > From: Stephen Warren <swarren@xxxxxxxxxx> > > > > Clock "emc" is for the External Memory Controller. The USB driver has no > > business touching this clock directly. Remove the code that does so. > > Stephen, > This was primarily done to make sure that EMC is set to a minimum > frequency, below which data errors may occur during USB transfers. > If we plan to remove this, how should we make sure that the EMC > is programmed for the required frequency during USB transfers? > You could use something like the API I added in "ARM: tegra: add EMC clock scaling API". This needs some rework and I looked into integrating this with the DEVFREQ framework, but I don't think it fits too well. Bandwidth requirements should always be communicated to the EMC driver and not described by clock rates. Regards, Lucas -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
