99 lines
3.2 KiB
Diff
99 lines
3.2 KiB
Diff
From 3bb347f520702ab886aa3513cf7d9035b09e624e Mon Sep 17 00:00:00 2001
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From: Maxime Ripard <maxime@cerno.tech>
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Date: Mon, 17 Jan 2022 17:36:23 +0100
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Subject: [PATCH] clk: bcm: rpi: Run some clocks at the minimum rate
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allowed
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The core clock and M2MC clocks are shared between some devices (Unicam
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controllers and the HVS, and the HDMI controllers, respectively) that
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will have various, varying, requirements depending on their current work
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load.
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Since those loads can require a fairly high clock rate in extreme
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conditions (up to ~600MHz), we can end up running those clocks at their
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maximum frequency even though we no longer require such a high rate.
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Fortunately, those devices don't require an exact rate but a minimum
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rate, and all the drivers are using clk_set_min_rate. Thus, we can just
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rely on the fact that the clk_request minimum (which is the aggregated
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minimum of all the clock users) is what we want at all times.
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Signed-off-by: Maxime Ripard <maxime@cerno.tech>
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---
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drivers/clk/bcm/clk-raspberrypi.c | 37 +++++++++++++++++++++++++++++++
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1 file changed, 37 insertions(+)
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--- a/drivers/clk/bcm/clk-raspberrypi.c
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+++ b/drivers/clk/bcm/clk-raspberrypi.c
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@@ -79,6 +79,7 @@ struct raspberrypi_clk_variant {
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bool export;
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char *clkdev;
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unsigned long min_rate;
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+ bool minimize;
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};
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static struct raspberrypi_clk_variant
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@@ -89,6 +90,18 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NU
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},
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[RPI_FIRMWARE_CORE_CLK_ID] = {
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.export = true,
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+
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+ /*
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+ * The clock is shared between the HVS and the CSI
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+ * controllers, on the BCM2711 and will change depending
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+ * on the pixels composited on the HVS and the capture
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+ * resolution on Unicam.
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+ *
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+ * Since the rate can get quite large, and we need to
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+ * coordinate between both driver instances, let's
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+ * always use the minimum the drivers will let us.
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+ */
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+ .minimize = true,
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},
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[RPI_FIRMWARE_M2MC_CLK_ID] = {
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.export = true,
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@@ -104,6 +117,16 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NU
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* in this situation.
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*/
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.min_rate = 120000000,
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+
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+ /*
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+ * The clock is shared between the two HDMI controllers
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+ * on the BCM2711 and will change depending on the
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+ * resolution output on each. Since the rate can get
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+ * quite large, and we need to coordinate between both
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+ * driver instances, let's always use the minimum the
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+ * drivers will let us.
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+ */
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+ .minimize = true,
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},
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[RPI_FIRMWARE_V3D_CLK_ID] = {
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.export = true,
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@@ -217,12 +240,26 @@ static int raspberrypi_fw_set_rate(struc
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static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
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struct clk_rate_request *req)
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{
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+ struct raspberrypi_clk_data *data =
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+ container_of(hw, struct raspberrypi_clk_data, hw);
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+ struct raspberrypi_clk_variant *variant = data->variant;
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+
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/*
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* The firmware will do the rounding but that isn't part of
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* the interface with the firmware, so we just do our best
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* here.
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*/
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+
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req->rate = clamp(req->rate, req->min_rate, req->max_rate);
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+
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+ /*
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+ * We want to aggressively reduce the clock rate here, so let's
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+ * just ignore the requested rate and return the bare minimum
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+ * rate we can get away with.
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+ */
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+ if (variant->minimize && req->min_rate > 0)
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+ req->rate = req->min_rate;
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+
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return 0;
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}
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