linux-kernel - Re: [PATCH v5 00/15] Add TPS25750 USB type-C PD controller support

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Message-ID: <ZQsOAi2bkBk8zHMr@primary>
Date:   Wed, 20 Sep 2023 11:21:38 -0400
From:   Abdel Alkuor <alkuor@...il.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     krzysztof.kozlowski+dt@...aro.org, bryan.odonoghue@...aro.org,
        gregkh@...uxfoundation.org, robh+dt@...nel.org,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        conor+dt@...nel.org, linux-kernel@...r.kernel.org,
        abdelalkuor@...tab.com, ryan.eleceng@...il.com
Subject: Re: [PATCH v5 00/15] Add TPS25750 USB type-C PD controller support

On Mon, Sep 18, 2023 at 04:57:49PM +0300, Heikki Krogerus wrote:
> On Sun, Sep 17, 2023 at 11:26:24AM -0400, Abdel Alkuor wrote:
> > From: Abdel Alkuor <abdelalkuor@...tab.com>
> > 
> > TPS25750 USB type-C PD controller has the same register offsets as
> > tps6598x. The following is a summary of incorporating TPS25750 into
> > TPS6598x driver:
> > 
> > - Only Check VID register (0x00) for TPS6598x and cd321x, as TPS25750 doesn't
> >   have VID register.
> > 
> > - TypeC port registration will be registered differently for each PD
> >   controller. TPS6598x uses system configuration register (0x28) to get
> >   pr/dr capabilities. On the other hand, TPS25750 will use data role property
> >   and PD status register (0x40) to get pr/dr capabilities as TPS25750 doesn't
> >   have register 0x28 supported.
> > 
> > - TPS25750 requires writing a binary configuration to switch PD
> >   controller from PTCH mode to APP mode which needs the following changes:
> >   - Add PTCH mode to the modes list.
> >   - Add an argument to tps6598x_check_mode to return the current mode.
> >   - Currently, tps6598x_exec_cmd has cmd timeout hardcoded to 1 second,
> >     and doesn't wait before checking DATA_OUT response. In TPS25750, patch 4CCs
> >     take longer than 1 second to execute and some requires a delay before
> >     checking DATA_OUT. To accommodate that, cmd_timeout and response_delay will
> >     be added as arguments to tps6598x_exec_cmd.
> >   - Implement applying patch sequence for TPS25750.
> > 
> > - In pm suspend callback, patch mode needs to be checked and the binary
> >   configuration should be applied if needed.
> > 
> > - For interrupt, TPS25750 has only one event register (0x14) and one mask
> >   register (0x16) of 11 bytes each, where TPS6598x has two event
> >   and two mask registers of 8 bytes each. Both TPS25750 and TPS65986x
> >   shares the same bit field offsets for events/masks/clear but many of
> >   there fields are reserved in TPS25750, the following needs to be done in
> >   tps6598x_interrupt:
> >   - Read EVENT1 register as a block of 11 bytes when tps25750 is present
> >   - Write CLEAR1 register as a block of 11 bytes when tps25750 is present
> >   - Add trace_tps25750_irq
> >   - During testing, I noticed that when a cable is plugged into the PD
> >     controller and before PD controller switches to APP mode, there is a
> >     lag between dr/pr updates and PlugInsertOrRemoval Event, so a check
> >     for dr/pr change needs to be added along TPS_REG_INT_PLUG_EVENT check
> > 
> > - Add TPS25750 traces for status and power status registers. Trace for
> >   data register won't be added as it doesn't exist in the device.
> > 
> > - Configure sleep mode for TPS25750.
> 
> This looks mostly okay, but I'm a bit uncomfortable with flags like
> is_tps25750.
> 
> I think a better way would be to supply driver data. In it you would
> have a callback for everything that needs to be customised.
> 
> struct tipd_data {
>         int (*interrupt)(int irq, void *data);
>         ...
> };
> ...
> static const struct tipd_data tps25750_data = {
>         .interrupt = tps25750_interrupt,
> ...
> 
> Something like that. You can on top of that still check
> device_is_compatible(dev, "...") in some places.
>
Sounds good. I will create callbacks factory struct as you suggested
and remove the flag.
> 
> thanks,
> 
> -- 
> heikki

Thanks,
Abdel