Date: Sun, 19 Aug 2018 19:27:44 +0530 From: Rajesh Kumar <rajfbsd@gmail.com> To: manu@bidouilliste.com Cc: danny@cs.huji.ac.il, ian@freebsd.org, freebsd-hackers@freebsd.org, freebsd-drivers@freebsd.org Subject: Re: Need a clarification regarding I2C bus frequency in FreeBSD Message-ID: <CAAO%2BANMnFSOB0MY3CizwrDjvzDET3X-ywAqOdjafPO9szARoyg@mail.gmail.com> In-Reply-To: <20180819122907.8c9306a0a307b9887443e818@bidouilliste.com> References: <CAAO%2BANOXwXAzJt%2BBZez6422jqKjrKPboSe_%2BudnOCWxYqE-=sQ@mail.gmail.com> <1534523216.27158.17.camel@freebsd.org> <3C2D99A1-DC1C-4915-81DE-7F9D48AAB10E@cs.huji.ac.il> <20180819122907.8c9306a0a307b9887443e818@bidouilliste.com>
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Hi Daniel/Emmanuel, Basically, I want to set the I2C clock frequency for Designware IP in our board to 150Mhz. So, I was looking for the way in FreeBSD. Is this 100Khz in arm/allwinner is same as what I am trying to configure? Or Is it something different? On Sun, Aug 19, 2018 at 3:59 PM Emmanuel Vadot <manu@bidouilliste.com> wrote: > On Sun, 19 Aug 2018 13:11:15 +0300 > Daniel Braniss <danny@cs.huji.ac.il> wrote: > > > > > > > > On 17 Aug 2018, at 19:26, Ian Lepore <ian@freebsd.org> wrote: > > > > > > On Fri, 2018-08-17 at 11:48 +0530, Rajesh Kumar wrote: > > >> Hi, > > >> > > >> I am trying to use the I2C designware controller driver available in > > >> FreeBSD (ig4_iic.c) in our boards. > > >> > > >> Is there a clean way, I can set the I2C bus frequency from the > controller > > >> driver itself, rather than using device hints, FDT, tunables etc., > > >> Something like, if the driver is loaded for our boards (identified > using > > >> the PCI or ACPI ID's), then the frequency of the I2C bus needs to be > > >> hardcoded from driver itself. This is to avoid additional configs > from the > > >> config file. > > >> > > >> I tried adding a new interface "iicbus_set_frequency" (in line with > > >> iicbus_get_frequency) and tried calling that from the ig4 driver > after the > > >> "iicbus" child is added. But, iicbus instance is created only after > ig4 > > >> driver is loaded. So, calling iicbus_set_frequency after child > addition > > >> leads to system panic (as there is no iicbus softc at this point). > > >> > > >> Let me know if you need any details. > > >> > > >> Thanks, > > >> Rajesh. > > > > > > I don't really understand what you're asking for. The ig4_iic > > > controller driver doesn't appear to support bus frequency settings at > > > all, it just loads hard-coded values into the clock high/low registers > > > and never changes them. If you want to locally modify the driver to run > > > at a different hard-coded speed for your application, just change lines > > > 589-592 in ig4_iic.c and continue to ignore the speed set by the bus > > > driver when handling iicbus_reset. > > > > > > > on the arm/allwinner it?s set at 100Khz, and though there are sysctls to > change it, > > it?s ignored :-) > > It is set at whatever frequency the dts set it and if there is no > frequency in the dts it fallback to 100Khz. > twsi needs to support IICBUS_GET_FREQUENCY though, the main reason I > never really touched twsi is because the same driver is used on Marvell > SoC with hackish support for the clocks. Now that I have a Marvell > board with this i2c controller I'll probably rewrite this driver. > > > I could change this, but is there some hidden reason that it?s so? > > > > danny > > > > _______________________________________________ > > freebsd-hackers@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > To unsubscribe, send any mail to " > freebsd-hackers-unsubscribe@freebsd.org" > > > -- > Emmanuel Vadot <manu@bidouilliste.com> <manu@freebsd.org> >
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