linux-kernel - Re: [PATCH v3 10/23] ata: libahci_platform: Parse ports-implemented property in resources getter

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Message-ID: <20220512143155.c6gbufrwju3z5wmi@mobilestation>
Date:   Thu, 12 May 2022 17:31:55 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Hannes Reinecke <hare@...e.de>
Cc:     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>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Patrice Chotard <patrice.chotard@...s.st.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,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v3 10/23] ata: libahci_platform: Parse ports-implemented
 property in resources getter

On Thu, May 12, 2022 at 08:48:24AM +0200, Hannes Reinecke wrote:
> On 5/12/22 01:17, Serge Semin wrote:
> > The ports-implemented property is mainly used on the OF-based platforms
> > with no ports mapping initialized by a bootloader/BIOS firmware. Seeing
> > the same of_property_read_u32()-based pattern has already been implemented
> > in the generic AHCI LLDD (glue) driver and in the Mediatek, St AHCI
> > drivers let's move the property read procedure to the generic
> > ahci_platform_get_resources() method. Thus we'll have the forced ports
> > mapping feature supported for each OF-based platform which requires that,
> > and stop re-implementing the same pattern in there a bit simplifying the
> > code.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > ---
> >   drivers/ata/ahci_mtk.c         | 2 --
> >   drivers/ata/ahci_platform.c    | 3 ---
> >   drivers/ata/ahci_st.c          | 3 ---
> >   drivers/ata/libahci_platform.c | 3 +++
> >   4 files changed, 3 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/ata/ahci_mtk.c b/drivers/ata/ahci_mtk.c
> > index 1f6c85fde983..c056378e3e72 100644
> > --- a/drivers/ata/ahci_mtk.c
> > +++ b/drivers/ata/ahci_mtk.c
> > @@ -118,8 +118,6 @@ static int mtk_ahci_parse_property(struct ahci_host_priv *hpriv,
> >   				   SYS_CFG_SATA_EN);
> >   	}
> > -	of_property_read_u32(np, "ports-implemented", &hpriv->force_port_map);
> > -
> >   	return 0;
> >   }
> > diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c
> > index 28a8de5b48b9..9b56490ecbc3 100644
> > --- a/drivers/ata/ahci_platform.c
> > +++ b/drivers/ata/ahci_platform.c
> > @@ -56,9 +56,6 @@ static int ahci_probe(struct platform_device *pdev)
> >   	if (rc)
> >   		return rc;
> > -	of_property_read_u32(dev->of_node,
> > -			     "ports-implemented", &hpriv->force_port_map);
> > -
> >   	if (of_device_is_compatible(dev->of_node, "hisilicon,hisi-ahci"))
> >   		hpriv->flags |= AHCI_HFLAG_NO_FBS | AHCI_HFLAG_NO_NCQ;
> > diff --git a/drivers/ata/ahci_st.c b/drivers/ata/ahci_st.c
> > index 7526653c843b..068621099c00 100644
> > --- a/drivers/ata/ahci_st.c
> > +++ b/drivers/ata/ahci_st.c
> > @@ -168,9 +168,6 @@ static int st_ahci_probe(struct platform_device *pdev)
> >   	st_ahci_configure_oob(hpriv->mmio);
> > -	of_property_read_u32(dev->of_node,
> > -			     "ports-implemented", &hpriv->force_port_map);
> > -
> >   	err = ahci_platform_init_host(pdev, hpriv, &st_ahci_port_info,
> >   				      &ahci_platform_sht);
> >   	if (err) {
> > diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> > index 4e54e19f07b2..f7f9cac10cb1 100644
> > --- a/drivers/ata/libahci_platform.c
> > +++ b/drivers/ata/libahci_platform.c
> > @@ -512,6 +512,9 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
> >   		goto err_out;
> >   	}

> > +	of_property_read_u32(dev->of_node,
> > +			     "ports-implemented", &hpriv->force_port_map);
> > +
> >   	if (child_nodes) {
> >   		for_each_child_of_node(dev->of_node, child) {
> >   			u32 port;
> 
> What happens on the other platforms?
> Won't they register an error if that property isn't implemented?

No. The force_port_map field will be left unmodified (zero by default) in case
if the optional 'ports-implemented' property is unavailable. See the
of_property_read_u32_array() method kdoc:
https://elixir.bootlin.com/linux/latest/source/include/linux/of.h#L1261

-Sergey

> 
> 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