[PATCH v8 0/2] PCI: brcmstb: Configure appropriate HW CLKREQ# mode

[Cyril Brulebois]

Hi Jim,

Jim Quinlan <james.quinlan at broadcom.com> (2023-11-13):
> V8 -- Un-advertise L1SS capability when in "no-l1ss" mode (Bjorn)
>    -- Squashed last two commits of v7 (Bjorn)
>    -- Fix DT binding description text wrapping (Bjorn)
>    -- Fix incorrect Spec reference (Bjorn)
>          s/PCIe Spec/PCIe Express Mini CEM 2.1 specification/
>    -- Text substitutions (Bjorn)
>          s/WRT/With respect to/ 
>          s/Tclron/T_CLRon/
> 
> v7 -- Manivannan Sadhasivam suggested (a) making the property look like a
>       network phy-mode and (b) keeping the code simple (not counting clkreq
>       signal appearances, un-advertising capabilites, etc).  This is
>       what I have done.  The property is now "brcm,clkreq-mode" and
>       the values may be one of "safe", "default", and "no-l1ss".  The
>       default setting is to employ the most capable power savings mode.

Still:

Tested-by: Cyril Brulebois <cyril at debamax.com>


I've just run my big test matrix again, and I can confirm everything is
still looking good with the updated series and the updated base commit.


Test setup:
-----------

 - using a $CM with the 20230111 EEPROM
 - on the same CM4 IO Board
 - with a $PCIE board (PCIe to multiple USB ports)
 - and the same Samsung USB flash drive + Logitech keyboard.

where $CM is one of:

 - CM4 Lite Rev 1.0
 - CM4 8/32 Rev 1.0
 - CM4 4/32 Rev 1.1

and $PCIE is one of:

 - SupaHub PCE6U1C-R02, VER 006
 - SupaHub PCE6U1C-R02, VER 006S
 - Waveshare VIA VL805/806-based


Results:
--------

 1. With an unpatched kernel, I'm getting either a successful boot
    *without* seeing the devices plugged on the PCIe-to-USB board
    or the dreaded SError in most cases, using a locally-built
    v6.4-rc7-194-g8a28a0b6f1a1d kernel.

 2. With a patched kernel (v6.6-15365-g305230142ae0 + this series),
    for all $CM/$PCIE combinations, I'm getting a system that boots,
    sees the flash drive, and gives decent read/write performance on
    it (plus a functional keyboard).


Cheers,
-- 
Cyril Brulebois (kibi at debian.org)            <https://debamax.com/>
D-I release manager -- Release team member -- Freelance Consultant
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