Re: [PATCH v4 03/68] clk: Move no reparent case into a separate function

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 05.05.2023 13:25, Maxime Ripard wrote:
> From: Stephen Boyd <sboyd@kernel.org>
>
> We'll need to turn the code in clk_mux_determine_rate_flags() to deal
> with CLK_SET_RATE_NO_REPARENT into a helper clock drivers will be able
> to use if they don't want to allow reparenting.
>
> Cc: Abel Vesa <abelvesa@kernel.org>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
> Cc: "Andreas Färber" <afaerber@suse.de>
> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Charles Keepax <ckeepax@opensource.cirrus.com>
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Chen-Yu Tsai <wenst@chromium.org>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: David Airlie <airlied@gmail.com>
> Cc: David Lechner <david@lechnology.com>
> Cc: Dinh Nguyen <dinguyen@kernel.org>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> Cc: Jaroslav Kysela <perex@perex.cz>
> Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
> Cc: Jonathan Hunter <jonathanh@nvidia.com>
> Cc: Kishon Vijay Abraham I <kishon@kernel.org>
> Cc: Liam Girdwood <lgirdwood@gmail.com>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Markus Schneider-Pargmann <msp@baylibre.com>
> Cc: Max Filippov <jcmvbkbc@gmail.com>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Mikko Perttunen <mperttunen@nvidia.com>
> Cc: Miles Chen <miles.chen@mediatek.com>
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Paul Cercueil <paul@crapouillou.net>
> Cc: Peng Fan <peng.fan@nxp.com>
> Cc: Peter De Schrijver <pdeschrijver@nvidia.com>
> Cc: Prashant Gaikwad <pgaikwad@nvidia.com>
> Cc: Richard Fitzgerald <rf@opensource.cirrus.com>
> Cc: Samuel Holland <samuel@sholland.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Sekhar Nori <nsekhar@ti.com>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Takashi Iwai <tiwai@suse.com>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Vinod Koul <vkoul@kernel.org>
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-actions@lists.infradead.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-mips@vger.kernel.org
> Cc: linux-phy@lists.infradead.org
> Cc: linux-renesas-soc@vger.kernel.org
> Cc: linux-rtc@vger.kernel.org
> Cc: linux-stm32@st-md-mailman.stormreply.com
> Cc: linux-sunxi@lists.linux.dev
> Cc: linux-tegra@vger.kernel.org
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: patches@opensource.cirrus.com
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Signed-off-by: Stephen Boyd <sboyd@kernel.org>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> ---

This patch landed in today's linux-next as commit 1b4e99fda73f ("clk: 
Move no reparent case into a separate function"). Unfortunately it 
causes serious regression of some of my test boards. Namely Exynos3250 
based boards are so slow after it, that my test scripts fail with a 
timeout waiting for them to finish booting. I will try to debug this 
later in the evening to check what has happened that some clocks got 
very low rate.


> drivers/clk/clk.c | 75 
> +++++++++++++++++++++++++++++++------------------------
> 1 file changed, 43 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index e495dd7a1eae..f57f821a5e5a 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -594,6 +594,46 @@ clk_core_forward_rate_req(struct clk_core *core,
> req->max_rate = old_req->max_rate;
> }
> +static int
> +clk_core_determine_rate_no_reparent(struct clk_hw *hw,
> + struct clk_rate_request *req)
> +{
> + struct clk_core *core = hw->core;
> + struct clk_core *parent = core->parent;
> + unsigned long best;
> + int ret;
> +
> + if (core->flags & CLK_SET_RATE_PARENT) {
> + struct clk_rate_request parent_req;
> +
> + if (!parent) {
> + req->rate = 0;
> + return 0;
> + }
> +
> + clk_core_forward_rate_req(core, req, parent, &parent_req,
> + req->rate);
> +
> + trace_clk_rate_request_start(&parent_req);
> +
> + ret = clk_core_round_rate_nolock(parent, &parent_req);
> + if (ret)
> + return ret;
> +
> + trace_clk_rate_request_done(&parent_req);
> +
> + best = parent_req.rate;
> + } else if (parent) {
> + best = clk_core_get_rate_nolock(parent);
> + } else {
> + best = clk_core_get_rate_nolock(core);
> + }
> +
> + req->rate = best;
> +
> + return 0;
> +}
> +
> int clk_mux_determine_rate_flags(struct clk_hw *hw,
> struct clk_rate_request *req,
> unsigned long flags)
> @@ -603,35 +643,8 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw,
> unsigned long best = 0;
> /* if NO_REPARENT flag set, pass through to current parent */
> - if (core->flags & CLK_SET_RATE_NO_REPARENT) {
> - parent = core->parent;
> - if (core->flags & CLK_SET_RATE_PARENT) {
> - struct clk_rate_request parent_req;
> -
> - if (!parent) {
> - req->rate = 0;
> - return 0;
> - }
> -
> - clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate);
> -
> - trace_clk_rate_request_start(&parent_req);
> -
> - ret = clk_core_round_rate_nolock(parent, &parent_req);
> - if (ret)
> - return ret;
> -
> - trace_clk_rate_request_done(&parent_req);
> -
> - best = parent_req.rate;
> - } else if (parent) {
> - best = clk_core_get_rate_nolock(parent);
> - } else {
> - best = clk_core_get_rate_nolock(core);
> - }
> -
> - goto out;
> - }
> + if (core->flags & CLK_SET_RATE_NO_REPARENT)
> + return clk_core_determine_rate_no_reparent(hw, req);
> /* find the parent that can provide the fastest rate <= rate */
> num_parents = core->num_parents;
> @@ -670,9 +683,7 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw,
> if (!best_parent)
> return -EINVAL;
> -out:
> - if (best_parent)
> - req->best_parent_hw = best_parent->hw;
> + req->best_parent_hw = best_parent->hw;
> req->best_parent_rate = best;
> req->rate = best;
>
Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland