Re: [PATCH v7 04/12] clk: Always clamp the rounded rate

[Yassine Oudjana <y.oudjana@protonmail.com>]

On Fri, 25 Feb 2022 15:35:26 +0100, Maxime Ripard <maxime@cerno.tech> wrote:
> The current core while setting the min and max rate properly in the
> clk_request structure will not make sure that the requested rate is
> within these boundaries, leaving it to each and every driver to make
> sure it is.
>
> It's not clear if this was on purpose or not, but this introduces some
> inconsistencies within the API.
>
> For example, a user setting a range and then calling clk_round_rate()
> with a value outside of that range will get the same value back
> (ignoring any driver adjustements), effectively ignoring the range that
> was just set.
>
> Another one, arguably worse, is that it also makes clk_round_rate() and
> clk_set_rate() behave differently if there's a range and the rate being
> used for both is outside that range. As we have seen, the rate will be
> returned unchanged by clk_round_rate(), but clk_set_rate() will error
> out returning -EINVAL.
>
> Let's make sure the framework will always clamp the rate to the current
> range found on the clock, which will fix both these inconsistencies.
>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> ---
>  drivers/clk/clk.c      |  2 ++
>  drivers/clk/clk_test.c | 50 +++++++++++++++++++++++++++---------------
>  2 files changed, 34 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 112911138a7b..6c4e10209568 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1348,6 +1348,8 @@ static int clk_core_determine_round_nolock(struct clk_core *core,
>  	if (!core)
>  		return 0;
>
> +	req->rate = clamp(req->rate, req->min_rate, req->max_rate);
> +

This breaks mmpll8_early on mmcc-msm8996, making GPU power up fail:

------------[ cut here ]------------
mmpll8_early failed to enable!
WARNING: CPU: 3 PID: 354 at drivers/clk/qcom/clk-alpha-pll.c:238 wait_for_pll+0xe8/0xfc
Modules linked in: q6asm_dai(+) ath10k_pci(+) q6afe_dai q6routing venus_enc panel_lgphilips_sw43101(+) venus_dec ath10k_core q6asm q6adm videobuf2_dma_contig qcom_camss snd_q6dsp_common snd_soc_wcd9335 q6afe snd_soc_apq8096 msm q6core ath regmap_slimbus v4l2_fwnode snd_soc_qcom_common apr snd_soc_core v4l2_async mac80211 venus_core videobuf2_dma_sg snd_compress v4l2_mem2mem videobuf2_memops videobuf2_v4l2 snd_pcm nxp_nci_i2c videobuf2_common libarc4 nxp_nci snd_timer gpu_sched videodev hci_uart drm_dp_helper snd i2c_qcom_cci nci btqca drm_kms_helper mc soundcore nfc syscopyarea sysfillrect bluetooth slim_qcom_ngd_ctrl sysimgblt pdr_interface fb_sys_fops slimbus lzo_rle qcom_spmi_haptics qcom_q6v5_mss qcom_spmi_temp_alarm qcom_q6v5_pas industrialio qcom_pil_info qcom_common qcom_q6v5 qcom_sysmon qmi_helpers mdt_loader socinfo pwm_ir_tx rmtfs_mem cfg80211 rfkill zram atmel_mxt_ts drm drm_panel_orientation_quirks ip_tables
CPU: 3 PID: 354 Comm: systemd-udevd Not tainted 5.18.0-rc1+ #361
Hardware name: Xiaomi Mi Note 2 (DT)
pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : wait_for_pll+0xe8/0xfc
lr : wait_for_pll+0xe8/0xfc
sp : ffff80000b01b250
x29: ffff80000b01b250 x28: ffff0000ae071960 x27: ffff000096a9ec00
x26: ffff0000801d7cf4 x25: 00000001cd074651 x24: 0000000000000000
x23: ffff800009129090 x22: ffff8000090d7c30 x21: 0000000000000000
x20: 0000000080000000 x19: ffff8000097b4598 x18: 0000000000000ca8
x17: 00000000000032a0 x16: 0000000000000007 x15: 00000000ffffffff
x14: 0000000000000001 x13: 0000000000000020 x12: fffffffffffcaebf
x11: ffff80000968afb0 x10: 000000000000000a x9 : ffff80000815bcc8
x8 : 000000000000000a x7 : 0000000000000006 x6 : 000000000000000c
x5 : ffff0000fdd16990 x4 : 0000000000000000 x3 : 0000000000000027
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000857e3b00
Call trace:
 wait_for_pll+0xe8/0xfc
 clk_alpha_pll_enable+0x118/0x150
 clk_core_enable+0x78/0x290
 clk_core_enable+0x58/0x290
 clk_core_enable+0x58/0x290
 clk_core_enable+0x58/0x290
 clk_enable+0x38/0x60
 clk_bulk_enable+0x48/0xb0
 msm_gpu_pm_resume+0xb4/0x20c [msm]
 a5xx_pm_resume+0x28/0x200 [msm]
 adreno_resume+0x2c/0x40 [msm]
 pm_generic_runtime_resume+0x38/0x50
 __genpd_runtime_resume+0x38/0x90
 genpd_runtime_resume+0xa4/0x2cc
 __rpm_callback+0x50/0x180
 rpm_callback+0x74/0x80
 rpm_resume+0x434/0x6b0
 __pm_runtime_resume+0x64/0xb0
 adreno_load_gpu+0x68/0x1b0 [msm]
 msm_open+0xf0/0x100 [msm]
 drm_file_alloc+0x150/0x234 [drm]
 drm_client_init+0xdc/0x180 [drm]
 drm_fb_helper_init+0x60/0x70 [drm_kms_helper]
 msm_fbdev_init+0x6c/0x100 [msm]
 msm_drm_bind+0x56c/0x640 [msm]
 try_to_bring_up_aggregate_device+0x230/0x320
 __component_add+0xac/0x194
 component_add+0x20/0x30
 dsi_dev_attach+0x2c/0x3c [msm]
 dsi_host_attach+0xa0/0x154 [msm]
 mipi_dsi_attach+0x34/0x50
 sw43101_probe+0x144/0x200 [panel_lgphilips_sw43101]
 mipi_dsi_drv_probe+0x2c/0x40
 really_probe+0x184/0x3d0
 __driver_probe_device+0x11c/0x190
 driver_probe_device+0x44/0xf4
 __driver_attach+0xd8/0x1f0
 bus_for_each_dev+0x7c/0xe0
 driver_attach+0x30/0x40
 bus_add_driver+0x150/0x230
 driver_register+0x84/0x140
 mipi_dsi_driver_register_full+0x64/0x70
 sw43101_driver_init+0x2c/0x1000 [panel_lgphilips_sw43101]
 do_one_initcall+0x50/0x2b0
 do_init_module+0x50/0x260
 load_module+0x229c/0x2ae0
 __do_sys_finit_module+0xac/0x12c
 __arm64_sys_finit_module+0x2c/0x3c
 invoke_syscall+0x50/0x120
 el0_svc_common.constprop.0+0xdc/0x100
 do_el0_svc+0x34/0xa0
 el0_svc+0x34/0xb0
 el0t_64_sync_handler+0xa4/0x130
 el0t_64_sync+0x18c/0x190
---[ end trace 0000000000000000 ]---
Failed to enable clk 'core': -110
msm 900000.mdss: [drm:adreno_load_gpu [msm]] *ERROR* Couldn't power up the GPU: -110