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Message-ID: <8e9567e3-cb75-7d74-1e50-728658a1b0e0@rock-chips.com>
Date: Tue, 15 Sep 2020 09:39:50 +0800
From: "elaine.zhang" <zhangqing@...k-chips.com>
To: Finley Xiao <finley.xiao@...k-chips.com>,
Jagan Teki <jagan@...rulasolutions.com>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Heiko Stuebner <heiko@...ech.de>,
张晴 <elaine.zhang@...k-chips.com>
Cc: linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-amarula <linux-amarula@...rulasolutions.com>
Subject: Re: [PATCH] clk: rockchip: Fix overflow rate during fractional
approximation
hi,
We have two submissions which I hope will be helpful to you.
https://patchwork.kernel.org/patch/11272465/
https://patchwork.kernel.org/patch/11272471/
A few more notes:
1. DCLK does not recommend the use of fractional frequency divider.
Generally, DCLK will monopolize a PLL, and the relationship between DCLK
frequency and PLL frequency is 1:1.
2, half-div, not all SOC support, detailed need to see TRM.
在 2020/9/15 上午9:20, Finley Xiao 写道:
>
> 在 2020/9/1 上午12:14, Jagan Teki 写道:
>> The current rockchip fractional approximation overflow the desired
>> rate if parent rate is lower than the (rate * 20) for few clocks like
>> dclk_vopb_frac.
>>
>> The overflow condition has observed in px30 for dclk_vopb_frac
>> clock with an input rate of 71.1MHz and parent rate of 24MHz is,
>>
>> [ 2.543280] rockchip-drm display-subsystem: bound ff460000.vop
>> (ops vop_component_ops)
>> [ 2.557313] rockchip-drm display-subsystem: bound ff470000.vop
>> (ops vop_component_ops)
>> [ 2.566356] rockchip-drm display-subsystem: bound
>> ff140000.syscon:lvds (ops rockchip_lvds_component_ops)
>> [ 2.576999] [drm] Supports vblank timestamp caching Rev 2
>> (21.10.2013).
>> [ 2.592177] Unexpected kernel BRK exception at EL1
>> [ 2.597551] Internal error: ptrace BRK handler: f20003e8 [#1]
>> PREEMPT SMP
>> [ 2.605143] Modules linked in:
>> [ 2.608566] CPU: 1 PID: 31 Comm: kworker/1:1 Tainted: G
>> U 5.8.0-rc1-15632-g97edd822b844 #30
>> [ 2.619363] Hardware name: Engicam PX30.Core C.TOUCH 2.0 10.1"
>> Open Frame (DT)
>> [ 2.627460] Workqueue: events deferred_probe_work_func
>> [ 2.633209] pstate: 20000005 (nzCv daif -PAN -UAO BTYPE=--)
>> [ 2.639445] pc : rational_best_approximation+0xc4/0xd0
>> [ 2.645194] lr : rockchip_fractional_approximation+0xa8/0xe0
>> [ 2.651520] sp : ffff800011ea31c0
>> [ 2.655222] x29: ffff800011ea31c0 x28: ffff00007a4ecd50
>> [ 2.661162] x27: ffff00007d042600 x26: 000000000439fca3
>> [ 2.667102] x25: 0000000000000000 x24: ffff800011ac9948
>> [ 2.673033] x23: ffff800011ea3308 x22: ffff00007d042418
>> [ 2.678973] x21: ffff800011ea3240 x20: ffff800011ea3238
>> [ 2.684904] x19: ea47000000000000 x18: 0000000000000000
>> [ 2.690836] x17: 0000000000000500 x16: 0000000000000001
>> [ 2.696775] x15: ffffffffffffffff x14: 0000000000000000
>> [ 2.702707] x13: 0000000000000000 x12: 0000003c00000000
>> [ 2.708647] x11: 0000000000000030 x10: 0101010101010101
>> [ 2.714586] x9 : 0000032000000320 x8 : 7f7f7f7f7f7f7f7f
>> [ 2.720517] x7 : 000000a3c59050d3 x6 : 0000000000000030
>> [ 2.726457] x5 : ffff800011ea3240 x4 : ffff800011ea3238
>> [ 2.732397] x3 : 000000000000ffff x2 : 000000000000ffff
>> [ 2.738329] x1 : 00000000016e3600 x0 : 0000000001497e00
>> [ 2.744269] Call trace:
>> [ 2.747005] rational_best_approximation+0xc4/0xd0
>> [ 2.752365] clk_fd_round_rate+0x8c/0x110
>> [ 2.756846] clk_composite_round_rate+0x30/0x40
>> [ 2.761917] clk_core_determine_round_nolock.part.30+0x44/0x80
>> [ 2.768442] clk_core_round_rate_nolock+0x78/0x80
>> [ 2.773701] clk_mux_determine_rate_flags+0xd8/0x200
>> [ 2.779253] clk_mux_determine_rate+0x10/0x20
>> [ 2.784124] clk_core_determine_round_nolock.part.30+0x1c/0x80
>> [ 2.790639] clk_core_round_rate_nolock+0x78/0x80
>> [ 2.795900] clk_core_round_rate_nolock+0x5c/0x80
>> [ 2.801159] clk_round_rate+0x64/0xf0
>> [ 2.805254] vop_crtc_mode_fixup+0x2c/0x60
>> [ 2.809828] drm_atomic_helper_check_modeset+0x95c/0xae0
>> [ 2.815767] drm_atomic_helper_check+0x1c/0xa0
>> [ 2.820738] drm_atomic_check_only+0x43c/0x760
>> [ 2.825705] drm_atomic_commit+0x18/0x60
>> [ 2.830095] drm_client_modeset_commit_atomic.isra.16+0x17c/0x250
>> [ 2.836911] drm_client_modeset_commit_locked+0x58/0x1a0
>> [ 2.842851] drm_client_modeset_commit+0x2c/0x50
>> [ 2.848014] drm_fb_helper_restore_fbdev_mode_unlocked+0x70/0xd0
>> [ 2.854730] drm_fb_helper_set_par+0x2c/0x60
>> [ 2.859497] fbcon_init+0x3c0/0x540
>> [ 2.863400] visual_init+0xac/0x100
>> [ 2.867298] do_bind_con_driver+0x1e4/0x3a0
>> [ 2.871973] do_take_over_console+0x140/0x200
>> [ 2.876843] do_fbcon_takeover+0x6c/0xe0
>> [ 2.881228] fbcon_fb_registered+0x10c/0x120
>> [ 2.886005] register_framebuffer+0x1f0/0x340
>> [ 2.890878] __drm_fb_helper_initial_config_and_unlock+0x318/0x4a0
>> [ 2.897790] drm_fb_helper_initial_config+0x3c/0x50
>> [ 2.903244] rockchip_drm_fbdev_init+0x5c/0xf0
>> [ 2.908202] rockchip_drm_bind+0x194/0x1e0
>> [ 2.912785] try_to_bring_up_master+0x164/0x1d0
>> [ 2.917851] component_master_add_with_match+0xac/0xf0
>> [ 2.923597] rockchip_drm_platform_probe+0x238/0x2e0
>> [ 2.929150] platform_drv_probe+0x50/0xa0
>> [ 2.933631] really_probe+0xd4/0x330
>> [ 2.937628] driver_probe_device+0x54/0xb0
>> [ 2.942207] __device_attach_driver+0x80/0xc0
>> [ 2.947078] bus_for_each_drv+0x78/0xd0
>> [ 2.951365] __device_attach+0xd4/0x130
>> [ 2.955652] device_initial_probe+0x10/0x20
>> [ 2.960328] bus_probe_device+0x90/0xa0
>> [ 2.964616] deferred_probe_work_func+0x6c/0xa0
>> [ 2.969685] process_one_work+0x1e4/0x360
>> [ 2.974166] worker_thread+0x208/0x480
>> [ 2.978358] kthread+0x150/0x160
>> [ 2.981968] ret_from_fork+0x10/0x18
>> [ 2.985970] Code: d65f03c0 d2800008 d2800027 17ffffe8 (d4207d00)
>>
>> This happened because the fractional divider does not apply if
>> parent_rate
>> is lower than (rate * 20).
>>
>> So, this patch is trying to fix that overflow clock and switch to
>> half-div
>> instead computing fractioanl approximation.
>>
>> Some part of the patch is referenced from below BSP commit:
>>
>> commit <88a5404a2277> ("clk: rockchip: fix up the
>> rockchip_fractional_approximation")
>>
>> commit <4186a0e4239b> ("clk: rockchip: Add supprot to limit input rate
>> for fractional divider")
>>
>> Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
>> Signed-off-by: Finley Xiao <finley.xiao@...k-chips.com>
>> ---
>> drivers/clk/rockchip/clk-px30.c | 12 ++++++------
>> drivers/clk/rockchip/clk.c | 9 +++++++++
>> 2 files changed, 15 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/clk/rockchip/clk-px30.c
>> b/drivers/clk/rockchip/clk-px30.c
>> index 6fb9c98b7d24..06d3ff39d12f 100644
>> --- a/drivers/clk/rockchip/clk-px30.c
>> +++ b/drivers/clk/rockchip/clk-px30.c
>> @@ -660,7 +660,7 @@ static struct rockchip_clk_branch
>> px30_clk_branches[] __initdata = {
>> COMPOSITE(SCLK_UART1_SRC, "clk_uart1_src", mux_uart_src_p,
>> CLK_SET_RATE_NO_REPARENT,
>> PX30_CLKSEL_CON(34), 14, 2, MFLAGS, 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(10), 12, GFLAGS),
>> - COMPOSITE_NOMUX_HALFDIV(0, "clk_uart1_np5", "clk_uart1_src", 0,
>> + COMPOSITE_NOMUX_HALFDIV(0, "clk_uart1_np5", "clk_uart1_src",
>> CLK_SET_RATE_PARENT,
>> PX30_CLKSEL_CON(35), 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(10), 13, GFLAGS),
>> COMPOSITE_FRACMUX(0, "clk_uart1_frac", "clk_uart1_src",
>> CLK_SET_RATE_PARENT,
>> @@ -673,7 +673,7 @@ static struct rockchip_clk_branch
>> px30_clk_branches[] __initdata = {
>> COMPOSITE(SCLK_UART2_SRC, "clk_uart2_src", mux_uart_src_p, 0,
>> PX30_CLKSEL_CON(37), 14, 2, MFLAGS, 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 0, GFLAGS),
>> - COMPOSITE_NOMUX_HALFDIV(0, "clk_uart2_np5", "clk_uart2_src", 0,
>> + COMPOSITE_NOMUX_HALFDIV(0, "clk_uart2_np5", "clk_uart2_src",
>> CLK_SET_RATE_PARENT,
>> PX30_CLKSEL_CON(38), 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 1, GFLAGS),
>> COMPOSITE_FRACMUX(0, "clk_uart2_frac", "clk_uart2_src",
>> CLK_SET_RATE_PARENT,
>> @@ -686,7 +686,7 @@ static struct rockchip_clk_branch
>> px30_clk_branches[] __initdata = {
>> COMPOSITE(0, "clk_uart3_src", mux_uart_src_p, 0,
>> PX30_CLKSEL_CON(40), 14, 2, MFLAGS, 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 4, GFLAGS),
>> - COMPOSITE_NOMUX_HALFDIV(0, "clk_uart3_np5", "clk_uart3_src", 0,
>> + COMPOSITE_NOMUX_HALFDIV(0, "clk_uart3_np5", "clk_uart3_src",
>> CLK_SET_RATE_PARENT,
>> PX30_CLKSEL_CON(41), 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 5, GFLAGS),
>> COMPOSITE_FRACMUX(0, "clk_uart3_frac", "clk_uart3_src",
>> CLK_SET_RATE_PARENT,
>> @@ -699,7 +699,7 @@ static struct rockchip_clk_branch
>> px30_clk_branches[] __initdata = {
>> COMPOSITE(0, "clk_uart4_src", mux_uart_src_p, 0,
>> PX30_CLKSEL_CON(43), 14, 2, MFLAGS, 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 8, GFLAGS),
>> - COMPOSITE_NOMUX_HALFDIV(0, "clk_uart4_np5", "clk_uart4_src", 0,
>> + COMPOSITE_NOMUX_HALFDIV(0, "clk_uart4_np5", "clk_uart4_src",
>> CLK_SET_RATE_PARENT,
>> PX30_CLKSEL_CON(44), 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 9, GFLAGS),
>> COMPOSITE_FRACMUX(0, "clk_uart4_frac", "clk_uart4_src",
>> CLK_SET_RATE_PARENT,
>> @@ -712,7 +712,7 @@ static struct rockchip_clk_branch
>> px30_clk_branches[] __initdata = {
>> COMPOSITE(0, "clk_uart5_src", mux_uart_src_p, 0,
>> PX30_CLKSEL_CON(46), 14, 2, MFLAGS, 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 12, GFLAGS),
>> - COMPOSITE_NOMUX_HALFDIV(0, "clk_uart5_np5", "clk_uart5_src", 0,
>> + COMPOSITE_NOMUX_HALFDIV(0, "clk_uart5_np5", "clk_uart5_src",
>> CLK_SET_RATE_PARENT,
>> PX30_CLKSEL_CON(47), 0, 5, DFLAGS,
>> PX30_CLKGATE_CON(11), 13, GFLAGS),
>> COMPOSITE_FRACMUX(0, "clk_uart5_frac", "clk_uart5_src",
>> CLK_SET_RATE_PARENT,
>> @@ -934,7 +934,7 @@ static struct rockchip_clk_branch
>> px30_clk_pmu_branches[] __initdata = {
>> COMPOSITE(0, "clk_uart0_pmu_src", mux_uart_src_p, 0,
>> PX30_PMU_CLKSEL_CON(3), 14, 2, MFLAGS, 0, 5, DFLAGS,
>> PX30_PMU_CLKGATE_CON(1), 0, GFLAGS),
>> - COMPOSITE_NOMUX_HALFDIV(0, "clk_uart0_np5", "clk_uart0_pmu_src", 0,
>> + COMPOSITE_NOMUX_HALFDIV(0, "clk_uart0_np5", "clk_uart0_pmu_src",
>> CLK_SET_RATE_PARENT,
>> PX30_PMU_CLKSEL_CON(4), 0, 5, DFLAGS,
>> PX30_PMU_CLKGATE_CON(1), 1, GFLAGS),
>> COMPOSITE_FRACMUX(0, "clk_uart0_frac", "clk_uart0_pmu_src",
>> CLK_SET_RATE_PARENT,
>> diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
>> index 546e810c3560..38d032faa05e 100644
>> --- a/drivers/clk/rockchip/clk.c
>> +++ b/drivers/clk/rockchip/clk.c
>> @@ -190,6 +190,15 @@ static void
>> rockchip_fractional_approximation(struct clk_hw *hw,
>> p_parent = clk_hw_get_parent(clk_hw_get_parent(hw));
>> p_parent_rate = clk_hw_get_rate(p_parent);
>> *parent_rate = p_parent_rate;
>> +
>> + /* fractional divider not apply if parent_rate is lower than
>> (rate * 20) */
>> + if (*parent_rate < rate * 20) {
>> + pr_warn("%s: %s fractional div is not allowed, so use
>> half-div\n",
>> + __func__, clk_hw_get_name(hw));
>> + *m = 0;
>> + *n = 1;
>> + return;
>> + }
>
> This is a public file, please submit separately.
>
> And there are no half-div on some rockchip platforms.
>
>> }
>> /*
>
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