From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Thu, 15 Jan 2015 16:51:56 +0100 Subject: [linux-sunxi] Re: [PATCH v3 05/13] ARM: dts: sun9i: Add clock-indices property for bus gate clocks In-Reply-To: References: <1421113055-17867-1-git-send-email-wens@csie.org> <1421113055-17867-6-git-send-email-wens@csie.org> <20150114163351.GY4891@lukather> <20150115152026.GA1135@lukather> Message-ID: <20150115155156.GA1837@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Jan 15, 2015 at 11:35:42PM +0800, Chen-Yu Tsai wrote: > On Thu, Jan 15, 2015 at 11:20 PM, Maxime Ripard > wrote: > > On Thu, Jan 15, 2015 at 10:24:04AM +0800, Chen-Yu Tsai wrote: > >> On Thu, Jan 15, 2015 at 12:33 AM, Maxime Ripard > >> wrote: > >> > On Tue, Jan 13, 2015 at 09:37:27AM +0800, Chen-Yu Tsai wrote: > >> >> of_clk_get_parent_name() uses the clock-indices property to resolve > >> >> clock phandle arguments in case that the argument index does not > >> >> match the clock-output-names sequence. > >> >> > >> >> This is the case on sunxi, where we use the actual bit index as the > >> >> argument to the phandle. Add the clock-indices property so that > >> >> of_clk_get_parent_name() resolves the names correctly. > >> >> > >> >> Signed-off-by: Chen-Yu Tsai > >> > > >> > Applied. Are the mask in the clock driver still of any use now? I > >> > don't think they are, and if we're going that way, I'd rather have > >> > them removed from the driver. > >> > >> Yes they are still passed through factors_data, for mux_clk_ops to > >> know about the width of the mux, which is 3 bits on older SoCs vs > >> 4 bits on sun9i. > > > > Erm.... These are gates. They are not muxable and are not handled > > through clk-factors, so I'm not sure how it is relevant :) > > Sorry. I jumped to the mux mask stuff. Yes the gate masks are still > used, and the gates are still referenced by the bit offset. > > As described in the commit message, clock-indices is used by > of_clk_get_parent_name() to match the index used in the phandle > to the correct name in clock-names. > > Take apb1 for example: > > clock-indices = <0>, <1>, <2>, <3>, <4>, > <16>, <17>, <18>, <19>, <20>, <21>; > clock-output-names = "apb1_i2c0", "apb1_i2c1", > "apb1_i2c2", "apb1_i2c3", "apb1_i2c4", > "apb1_uart0", "apb1_uart1", ... > > If we have "clocks = <&apb1 16>;" in some device, and we call > of_clk_get_parent_name() on said clock, it would try to get > clock_output_names[16], which obviously is the wrong one. > > With clock-indices, of_clk_get_parent_name first looks at > that array, finds an entry matching 16, then uses the > index of the matching entry to get the name from > clock-output-names. Yeah, I know what it does, and we do agree on the fact that it's needed. > So, we are still using the gate bitmask to declare valid > clock gates. The sunxi driver does not use clock-indices > directly. Nor do I think it was intended to be used by > clock drivers directly. However, the gate bitmask itself carries exactly the same information than clock-indices. It's the exact same list of numbers, just with two different ways of defining it. If we go with clock-indices, which is the right solution, then we can just drop the other one. I actually started to do just this last evening. A31 boots without any gates bit mask but the USB clocks one so far, I intend on converting the others as well. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: