Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752009AbcJJLdM (ORCPT ); Mon, 10 Oct 2016 07:33:12 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:49727 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751488AbcJJLdI (ORCPT ); Mon, 10 Oct 2016 07:33:08 -0400 Subject: Re: [PATCH] Reorganize STM32 clocks in order to prepare them for PLLI2S and PLLSAI To: Daniel Thompson , =?UTF-8?Q?Rados=c5=82aw_Pietrzyk?= , Gabriel FERNANDEZ References: <1475791294-5804-1-git-send-email-user@localhost> <2d6d5c10-346e-0541-1bc0-b75ef5b40d3f@linaro.org> CC: Michael Turquette , , Maxime Coquelin , , , From: Alexandre Torgue Message-ID: <1880a125-b5ec-b64a-5c9b-90d4e9c0af86@st.com> Date: Mon, 10 Oct 2016 13:32:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.48.0.2] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-10-10_07:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2347 Lines: 65 Hi Radoslaw, I add Gabriel in the discussion. Gabriel is updating PLL management for STM32F429. Regards Alex On 10/10/2016 12:31 PM, Daniel Thompson wrote: > On 10/10/16 10:56, Radosław Pietrzyk wrote: >> Hi, >> all plls have the same clock parent which is after a main divider. >> Currently the divider and multiplier are connected together within vco >> clock and therefore there is no chance to reuse the divider and clearly >> state where the conncetion "really" is. We can arrange all of them >> separately but than the divider will be hidden for all of them >> separately. > > Quoting my last mail "I can see the value of naming the "/M" > pre-division separately". In other words I agree with the idea of the > patch. > > To more explicitly state my review comments... > >> From: Radoslaw Pietrzyk > > Please add a explanation of the problem and solution in the patch > description. > > >> Signed-off-by: Radoslaw Pietrzyk >> --- >> drivers/clk/clk-stm32f4.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c >> index 02d6810..1fd3eac 100644 >> --- a/drivers/clk/clk-stm32f4.c >> +++ b/drivers/clk/clk-stm32f4.c >> @@ -245,9 +245,10 @@ static void stm32f4_rcc_register_pll(const char > *hse_clk, const char *hsi_clk) >> const char *pllsrc = pllcfgr & BIT(22) ? hse_clk : hsi_clk; >> unsigned long pllq = (pllcfgr >> 24) & 0xf; >> >> - clk_register_fixed_factor(NULL, "vco", pllsrc, 0, plln, pllm); >> - clk_register_fixed_factor(NULL, "pll", "vco", 0, 1, pllp); >> - clk_register_fixed_factor(NULL, "pll48", "vco", 0, 1, pllq); >> + clk_register_fixed_factor(NULL, "vco-div", pllsrc, 0, 1, pllm); > > This strikes me as a bad name for a clock that is shared by all three > PLLs (the vco being an internal component of the PLL) however since the > clock is not named in the datasheet we are forced to invent a name [I > suspect that's why I gave up trying to name it when I wrote the driver > originally ;-) ]. > > Perhaps "pllin-prediv"? > > >> + clk_register_fixed_factor(NULL, "vco-mul", "vco-div", 0, plln, 1); > > Why rename this clock? Multiplying is a what the vco (and its control > circuits) is *for*. Tagging it "-mul" is meaningless. > > > Daniel.