linux-kernel - Re: [PATCH v3 14/23] ata: libahci: Discard redundant force_port

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Message-ID: <12c73812-c544-5859-3fc0-38b65785f987@suse.de>
Date:   Thu, 12 May 2022 09:00:15 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        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 v3 14/23] ata: libahci: Discard redundant force_port_map
 parameter

On 5/12/22 01:18, 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 low level drivers (platform drivers) then it will
> have greater priority over the value read from PI register and will be
> used as actual HBA ports mapping later on. Thus the ports map forcing task
> will be just transferred from the force_port_map to saved_port_map field.
> 
> This modification will perfectly fit into the feature of having OF-based
> initialization of the HW-init HBA CSR fields we are about to introduce in
> the next commit.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> ---
>   drivers/ata/ahci.c             |  2 +-
>   drivers/ata/ahci.h             |  1 -
>   drivers/ata/libahci.c          | 10 ++++++----
>   drivers/ata/libahci_platform.c |  2 +-
>   4 files changed, 8 insertions(+), 7 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@...e.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer