ata: ahci: Cleanup ahci_reset_controller()

Fix multi-line comment style in ahci_reset_controller() and change the
code to return early if ahci_skip_host_reset is true, reducing
indentation by one level for the bulk of the function code.

No functional changes.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/ata/libahci.c | 61 +++++++++++++++++++++----------------------
 1 file changed, 30 insertions(+), 31 deletions(-)

On Tue, Jun 13, 2023 at 03:34:36PM +0900, Damien Le Moal wrote:
> Fix multi-line comment style in ahci_reset_controller() and change the
> code to return early if ahci_skip_host_reset is true, reducing
> indentation by one level for the bulk of the function code.
> 
> No functional changes.
> 
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> ---
>  drivers/ata/libahci.c | 61 +++++++++++++++++++++----------------------
>  1 file changed, 30 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 9c2cb6cbea76..bd38ff72e543 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -975,44 +975,43 @@ int ahci_reset_controller(struct ata_host *host)
>  	void __iomem *mmio = hpriv->mmio;
>  	u32 tmp;
>  
> -	/* we must be in AHCI mode, before using anything
> -	 * AHCI-specific, such as HOST_RESET.
> +	/*
> +	 * We must be in AHCI mode, before using anything AHCI-specific, such
> +	 * as HOST_RESET.
>  	 */
>  	ahci_enable_ahci(mmio);
>  
> -	/* global controller reset */
> -	if (!ahci_skip_host_reset) {
> -		tmp = readl(mmio + HOST_CTL);
> -		if ((tmp & HOST_RESET) == 0) {
> -			writel(tmp | HOST_RESET, mmio + HOST_CTL);
> -			readl(mmio + HOST_CTL); /* flush */
> -		}
> +	/* Global controller reset */
> +	if (ahci_skip_host_reset) {
> +		dev_info(host->dev, "Skipping global host reset\n");
> +		return 0;
> +	}
>  
> -		/*
> -		 * to perform host reset, OS should set HOST_RESET
> -		 * and poll until this bit is read to be "0".
> -		 * reset must complete within 1 second, or
> -		 * the hardware should be considered fried.
> -		 */
> -		tmp = ata_wait_register(NULL, mmio + HOST_CTL, HOST_RESET,
> -					HOST_RESET, 10, 1000);
> +	tmp = readl(mmio + HOST_CTL);
> +	if ((tmp & HOST_RESET) == 0) {

Nit: perhaps use if (!(tmp & HOST_RESET)) instead, such that we use the
same pattern as:
if (!(hpriv->flags & AHCI_HFLAG_NO_WRITE_TO_RO))
below.

> +		writel(tmp | HOST_RESET, mmio + HOST_CTL);
> +		readl(mmio + HOST_CTL); /* flush */
> +	}
>  
> -		if (tmp & HOST_RESET) {
> -			dev_err(host->dev, "controller reset failed (0x%x)\n",
> -				tmp);
> -			return -EIO;
> -		}
> +	/*
> +	 * To perform host reset, OS should set HOST_RESET and poll until this
> +	 * bit is read to be "0". Reset must complete within 1 second, or the
> +	 * hardware should be considered fried.
> +	 */
> +	tmp = ata_wait_register(NULL, mmio + HOST_CTL, HOST_RESET,
> +				HOST_RESET, 10, 1000);
> +	if (tmp & HOST_RESET) {
> +		dev_err(host->dev, "Controller reset failed (0x%x)\n",
> +			tmp);
> +		return -EIO;
> +	}
>  
> -		/* turn on AHCI mode */
> -		ahci_enable_ahci(mmio);
> +	/* Turn on AHCI mode */
> +	ahci_enable_ahci(mmio);
>  
> -		/* Some registers might be cleared on reset.  Restore
> -		 * initial values.
> -		 */
> -		if (!(hpriv->flags & AHCI_HFLAG_NO_WRITE_TO_RO))
> -			ahci_restore_initial_config(host);
> -	} else
> -		dev_info(host->dev, "skipping global host reset\n");
> +	/* Some registers might be cleared on reset. Restore initial values. */
> +	if (!(hpriv->flags & AHCI_HFLAG_NO_WRITE_TO_RO))
> +		ahci_restore_initial_config(host);
>  
>  	return 0;
>  }
> -- 
> 2.40.1
> 

Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>