linux-kernel - Re: [PATCH] ahci: libahci: clear pending interrupt status

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Date:   Thu, 31 Aug 2023 14:22:00 +0900
From:   Damien Le Moal <dlemoal@...nel.org>
To:     Szuying Chen <chensiying21@...il.com>, Niklas.Cassel@....com,
        linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jesse1_Chang@...edia.com.tw, Richard_Hsu@...edia.com.tw,
        Chloe_Chen@...edia.com.tw
Subject: Re: [PATCH] ahci: libahci: clear pending interrupt status

On 8/31/23 12:09, Szuying Chen wrote:
> This patch adds the function to clear pending interrupt before COMRESET.
> It follows the  AHCI1.3.1 - section6.2.2.2 specification.

Please explain here the relevant part of that section.

> 
> Signed-off-by: Szuying Chen <Chloe_Chen@...edia.com.tw>
> ---
>  drivers/ata/libahci.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 06aec35f88f2..1ae788251a6c 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -1584,6 +1584,23 @@ static int ahci_pmp_retry_softreset(struct ata_link *link, unsigned int *class,
>  	return rc;
>  }
> 
> +static void PortClearPendingInterrupt(struct ata_port *ap)

No CaMeLCaSe please ! Call this ahci_port_clear_peinding_irq().

> +{
> +	struct ahci_host_priv *hpriv = ap->host->private_data;
> +	void __iomem *port_mmio = ahci_port_base(ap);
> +	u32 tmp;
> +
> +	/* clear port SERR */
> +	tmp = readl(port_mmio + PORT_SCR_ERR);
> +	writel(tmp, port_mmio + PORT_SCR_ERR);
> +
> +	/* clear port IRQ */
> +	tmp = readl(port_mmio + PORT_IRQ_STAT);
> +	writel(tmp, port_mmio + PORT_IRQ_STAT);
> +
> +	writel(1 << ap->port_no, hpriv->mmio + HOST_IRQ_STAT);

This code is nearly identical to what ahci_port_init() does. So better make it
common: keep the debug messages that are in ahci_port_init() and modify that
function to call this new helper.

> +}
> +
>  int ahci_do_hardreset(struct ata_link *link, unsigned int *class,
>  		      unsigned long deadline, bool *online)
>  {
> @@ -1602,6 +1619,9 @@ int ahci_do_hardreset(struct ata_link *link, unsigned int *class,
>  	tf.status = ATA_BUSY;
>  	ata_tf_to_fis(&tf, 0, 0, d2h_fis);
> 
> +	/* clear pending Interrupt */
> +	PortClearPendingInterrupt(ap);
> +
>  	rc = sata_link_hardreset(link, timing, deadline, online,
>  				 ahci_check_ready);
> 
> --
> 2.39.2
> 

-- 
Damien Le Moal
Western Digital Research