From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C642C433EF for ; Tue, 8 Feb 2022 11:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356148AbiBHLv3 convert rfc822-to-8bit (ORCPT ); Tue, 8 Feb 2022 06:51:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356935AbiBHLuO (ORCPT ); Tue, 8 Feb 2022 06:50:14 -0500 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F9D8C035417 for ; Tue, 8 Feb 2022 03:41:15 -0800 (PST) Received: from ip5b412258.dynamic.kabel-deutschland.de ([91.65.34.88] helo=diego.localnet) by gloria.sntech.de with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nHOrt-00014g-Pz; Tue, 08 Feb 2022 12:41:09 +0100 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Sascha Hauer Cc: dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org, kernel@pengutronix.de, Andy Yan , Benjamin Gaignard , Michael Riesch , Sandy Huang , Peter Geis Subject: Re: [PATCH 24/27] clk: rk3568: drop CLK_SET_RATE_PARENT from dclk_vop* Date: Tue, 08 Feb 2022 12:41:08 +0100 Message-ID: <2260638.yNqFStFpQL@diego> In-Reply-To: <20220131081042.GW23490@pengutronix.de> References: <20220126145549.617165-1-s.hauer@pengutronix.de> <5329207.qDA9hNt6id@diego> <20220131081042.GW23490@pengutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Am Montag, 31. Januar 2022, 09:10:42 CET schrieb Sascha Hauer: > On Sat, Jan 29, 2022 at 06:48:13PM +0100, Heiko Stübner wrote: > > Am Mittwoch, 26. Januar 2022, 15:55:46 CET schrieb Sascha Hauer: > > > The pixel clocks dclk_vop[012] can be clocked from hpll, vpll, gpll or > > > cpll. gpll and cpll also drive many other clocks, so changing the > > > dclk_vop[012] clocks could change these other clocks as well. Drop > > > CLK_SET_RATE_PARENT to fix that. With this change the VOP2 driver can > > > only adjust the pixel clocks with the divider between the PLL and the > > > dclk_vop[012] which means the user may have to adjust the PLL clock to a > > > suitable rate using the assigned-clock-rate device tree property. > > > > > > Signed-off-by: Sascha Hauer > > > --- > > > drivers/clk/rockchip/clk-rk3568.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/clk/rockchip/clk-rk3568.c b/drivers/clk/rockchip/clk-rk3568.c > > > index 9d889fc46811..7687c62d1fa8 100644 > > > --- a/drivers/clk/rockchip/clk-rk3568.c > > > +++ b/drivers/clk/rockchip/clk-rk3568.c > > > @@ -1044,13 +1044,13 @@ static struct rockchip_clk_branch rk3568_clk_branches[] __initdata = { > > > RK3568_CLKGATE_CON(20), 8, GFLAGS), > > > GATE(HCLK_VOP, "hclk_vop", "hclk_vo", 0, > > > RK3568_CLKGATE_CON(20), 9, GFLAGS), > > > - COMPOSITE(DCLK_VOP0, "dclk_vop0", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT, > > > + COMPOSITE(DCLK_VOP0, "dclk_vop0", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_NO_REPARENT, > > > > hmm, I'm wondering about the use of having CLK_SET_RATE_NO_REPARENT here > > (and even adding it below). > > > > Using SET_RATE_PARENT in the following patch for the hdmi-pll, should give > > us at least a suitable rate for the hdmi output, so the vop using that > > should already find a nice rate to use. > > > > The normal system-PLLs don't normally don't change their rate at runtime, > > so I think we should liberate the dclks to select a PLL that best matches > > their target rate - so drop the CLK_SET_RATE_NO_REPARENT as well. > > > > That way the DCLKs can change to another PLL source if that provides > > a rate nearer to their target. > > The HDMI reference clock has the CLK_SET_RATE_PARENT flag set and we > need that to program the HPLL clock to suitable rates for the HDMI > output. Now any other display choosing HPLL as parent, because that > provides the best rate in that point of time, hangs on a PLL which > changes its rate whenever the resolution is changed on the HDMI output. Ah, right ... the hpll is in the parent list, that changes things as you said. I somehow only noticed the regular PLLs that normally have a constant rate. So never mind ;-) Heiko > Changing parents on rate changes only works when all possible parents of > all the children involved have a constant rate. IMO allowing reparenting > on rate changes is a poorly chosen default because it's very unsafe. We > should rather have a CLK_SET_RATE_ALLOW_REPARENT flag. > > Sascha > >