From mboxrd@z Thu Jan 1 00:00:00 1970 From: laurent.pinchart@ideasonboard.com (Laurent Pinchart) Date: Wed, 22 Oct 2014 23:59:35 +0300 Subject: [PATCH v2] ARM: shmobile: Add early debugging support using SCIF(A) In-Reply-To: References: <1413993263-10444-1-git-send-email-geert+renesas@glider.be> <20141022160800.GB1895@katana> Message-ID: <1467605.AdUxz6EOpv@avalon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Geert, On Wednesday 22 October 2014 19:34:17 Geert Uytterhoeven wrote: > On Wed, Oct 22, 2014 at 6:08 PM, Wolfram Sang wrote: > >> I'm wondering whether this can be fixed in the i2c driver? Does it really > >> have to enable and disable the clock? > > > > From a power-saving PoV, this makes sense. I assume serial output works > > again as soon as the regular scif driver takes over? Isn't that a > > Yes it continues fine afterwards. > With TMU0 in DT, it's enabled again even earlier, as they share the parent. Would it make sense to have a list of clocks to reference from setup code when DEBUG_LL is defined ? It's a bit hackish, but DEBUG_LL is hackish anyway. > > generic problem of early_printk drivers that they are not refcounted for > > the clocks? > > Yes. > > BTW, the code in sh_mobile_i2c_init() does this: > > /* Get clock rate after clock is enabled */ > clk_prepare_enable(pd->clk); > i2c_clk_khz = clk_get_rate(pd->clk) / 1000; > clk_disable_unprepare(pd->clk); > > I assume the enable/disable is no longer needed with CCF? I assume so as well. -- Regards, Laurent Pinchart