linux-kernel - Re: `intel_lpss_pci_driver

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Message-ID: <ZcUQen0nYAAtZVw8@smile.fi.intel.com>
Date: Thu, 8 Feb 2024 19:33:46 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Lee Jones <lee@...nel.org>
Cc: Paul Menzel <pmenzel@...gen.mpg.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: `intel_lpss_pci_driver_init` takes 23.8 ms

On Thu, Feb 08, 2024 at 08:59:28AM +0000, Lee Jones wrote:
> On Tue, 06 Feb 2024, Paul Menzel wrote:

> > On the Dell XPS 13 9360 and Linux 6.8-rc3+, `intel_lpss_pci_driver_init()`
> > takes 23.8 ms, making it one of Linux’ longer init functions on this device:

Does it mean on the previous releases it was different?
I mean is it a regression or always was like this?

> > 
> > ```
> > [    0.000000] Linux version 6.8.0-rc3
> > (build@...emianrhapsody.molgen.mpg.de) (gcc (Debian 13.2.0-13) 13.2.0, GNU
> > ld (GNU Binutils for Debian) 2.42) #13 SMP PREEMPT_DYNAMIC Tue Feb 6
> > 08:07:48 CET 2024
> > [    0.000000] Command line: BOOT_IMAGE=/vmlinuz-6.8.0-rc3
> > root=UUID=32e29882-d94d-4a92-9ee4-4d03002bfa29 ro quiet pci=noaer
> > mem_sleep_default=deep log_buf_len=8M cryptomgr.notests initcall_debug
> > […]
> > [    0.000000] DMI: Dell Inc. XPS 13 9360/0596KF, BIOS 2.21.0 06/02/2022
> > […]
> > [    0.785696] calling  intel_lpss_pci_driver_init+0x0/0xff0
> > [intel_lpss_pci] @ 153
> > [    0.785704] calling  crct10dif_intel_mod_init+0x0/0xff0
> > [crct10dif_pclmul] @ 163
> > [    0.785796] calling  drm_core_init+0x0/0xff0 [drm] @ 161
> > [    0.785880] ACPI: bus type drm_connector registered
> > [    0.785887] initcall drm_core_init+0x0/0xff0 [drm] returned 0 after 25
> > usecs
> > [    0.785936] intel-lpss 0000:00:15.0: enabling device (0000 -> 0002)
> > [    0.786210] idma64 idma64.0: Found Intel integrated DMA 64-bit
> > [    0.786221] probe of idma64.0 returned 0 after 81 usecs
> > […]
> > [    0.801676] probe of i2c_designware.0 returned 0 after 15424 usecs
> > [    0.801691] probe of 0000:00:15.0 returned 0 after 15973 usecs
> > [    0.801870] intel-lpss 0000:00:15.1: enabling device (0000 -> 0002)
> > [    0.802116] idma64 idma64.1: Found Intel integrated DMA 64-bit
> > [    0.802123] probe of idma64.1 returned 0 after 55 usecs
> > [    0.819818] probe of i2c_designware.1 returned 0 after 17646 usecs
> > [    0.819832] probe of 0000:00:15.1 returned 0 after 18137 usecs
> > [    0.819852] initcall intel_lpss_pci_driver_init+0x0/0xff0
> > [intel_lpss_pci] returned 0 after 23842 usecs
> > ```
> > 
> > Is this expected, that probing
> > 
> >     00:15.1 Signal processing controller [1180]: Intel Corporation Sunrise
> > Point-LP Serial IO I2C Controller #1 [8086:9d61] (rev 21)
> > 
> > takes 18 ms?

And it seems that the real culprit is the DesingWare driver itself, am I wrong?

-- 
With Best Regards,
Andy Shevchenko