linux-kernel - Re: [PATCH 12/21] ata: libahci: Discard redundant force_port

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Date:   Tue, 12 Apr 2022 07:48:50 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Serge Semin <fancer.lancer@...il.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Rob Herring <robh+dt@...nel.org>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 12/21] ata: libahci: Discard redundant force_port_map
 parameter

On 4/12/22 05:52, Serge Semin wrote:
> On Mon, Apr 11, 2022 at 09:25:03PM +0900, Damien Le Moal wrote:
>> On 4/11/22 21:11, Serge Semin wrote:
>>> On Thu, Mar 24, 2022 at 11:05:58AM +0900, Damien Le Moal wrote:
>>>> On 3/24/22 09:16, Serge Semin wrote:
>>>>> Currently there are four port-map-related fields declared in the
>>>>> ahci_host_priv structure and used to setup the HBA ports mapping. First
>>>>> the ports-mapping is read from the PI register and immediately stored in
>>>>> the saved_port_map field. If forced_port_map is initialized with non-zero
>>>>> value then its value will have greater priority over the value read from
>>>>> PI, thus it will override the saved_port_map field. That value will be then
>>>>> masked by a non-zero mask_port_map field and after some sanity checks it
>>>>> will be stored in the ahci_host_priv.port_map field as a final port
>>>>> mapping.
>>>>>
>>>>> As you can see the logic is a bit too complicated for such a simple task.
>>>>> We can freely get rid from at least one of the fields with no change to
>>>>> the implemented semantic. The force_port_map field can be replaced with
>>>>> taking non-zero saved_port_map value into account. So if saved_port_map is
>>>>> pre-initialized by the glue-driver/platform-specific code then it will
>>>>
>>>
>>>> glue-driver == LLDD (low level device driver), for the entire series please.
>>>
>>> Why? It's a normal term and well known amongst developers. I've used it
>>> in a plenty of my patches before and none of them has been questioned in that
>>> part so far.
>>
> 
>> This term is not used in libata, nor do I remember seeing it used in SCSI
>> or block subsystem either. We always talk about mid-layer (ahci platform)
>> and LLDD (adapter driver).
> 
> Great, do we need to learn the subsystem-specific dictionary now
> before submitting the patches for it? =)
> Really, you are asking me to change one term to its synonym just
> because it's mainly unused here. Now you know what it means, the
> others can easily google it and get to learn something new. Win-win.)

I already knew what it meant, but it was unclear if my idea of what you
meant was actually the same as yours. Sticking with the vocabulary already
used since *a long time ago* makes life easier for reviewers and avoids
confusion.

-- 
Damien Le Moal
Western Digital Research