Subject: [PATCH 1/2] ahci_xgene: Fix the xgene_ahci_restart_engine function to support Port Multiplier for APM X-Gene SoC AHCI SATA host controller driver.

From: [email-masked] (Sergei Shtylyov)
Date: Mon, 05 Jan 2015 17:50:23 +0300

Hello.

On 1/5/2015 1:21 PM, Suman Tripathi wrote:

    Your patch summary seems too long.

> This patch implements the function xgene_ahci_poll_reg_val to poll
> PxCI for multiple IDENTIFY DEVICE commands to finish before
> restarting the DMA engine in case of Port Multiplier.

> Signed-off-by: Suman Tripathi <[email-masked]>
> ---
>   drivers/ata/ahci_xgene.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 54 insertions(+), 2 deletions(-)

> diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
> index 0f8538f..2180223 100644
> --- a/drivers/ata/ahci_xgene.c
> +++ b/drivers/ata/ahci_xgene.c
> @@ -105,17 +105,69 @@ static int xgene_ahci_init_memram(struct xgene_ahci_context *ctx)
>   }
>
>   /**
> + * xgene_ahci_poll_reg_val- Poll a register on a specific value.
> + * @ap : ATA port of interest.
> + * @reg : Register of interest.
> + * @val : Value to be attained.
> + * @interval : waiting interval for polling.
> + * @timeout : timeout for achieving the value.
> + */
> +static int xgene_ahci_poll_reg_val(struct ata_port *ap,
> +				   void __iomem *reg, unsigned
> +				   int val, unsigned long interval,
> +				   unsigned long timeout)
> +{
> +	unsigned long deadline;
> +	unsigned int tmp;
> +
> +	tmp = ioread32(reg);
> +	deadline = ata_deadline(jiffies, timeout);
> +
> +	while ((tmp != val) && (time_before(jiffies, deadline))) {

    Parens around the operands of && are not needed, especially around the 
right one.

> +		ata_msleep(ap, interval);
> +		tmp = ioread32(reg);
> +	}
> +
> +	return tmp;
> +}
> +
> +/**
>    * xgene_ahci_restart_engine - Restart the dma engine.
>    * @ap : ATA port of interest
>    *
> - * Restarts the dma engine inside the controller.
> + * Waits for completion of multiple commands and restarts
> + * the DMA engine inside the controller.
>    */
>   static int xgene_ahci_restart_engine(struct ata_port *ap)
>   {
>   	struct ahci_host_priv *hpriv = ap->host->private_data;
> +	struct ahci_port_priv *pp = ap->private_data;
> +	void __iomem *port_mmio = ahci_port_base(ap);
> +	u32 fbs;
> +
> +	/*
> +	 * In case of PMP multiple IDENTIFY DEVICE commands can be
> +	 * issued inside PxCI. So need to poll PxCI for the
> +	 * completion of outstanding IDENTIFY DEVICE commands before
> +	 * we restart the DMA engine.
> +	 */
> +	if (xgene_ahci_poll_reg_val(ap, port_mmio +
> +				    PORT_CMD_ISSUE, 0x0, 1, 100))
> +		  return -EBUSY;
>
>   	ahci_stop_engine(ap);
>   	ahci_start_fis_rx(ap);
> +
> +	/*
> +	 * Enable the PxFBS.FBS_EN bit as it
> +	 * gets cleared due to stop engine.

    s/stop/stopping the/.

[...]

MBR, Sergei