Patchwork [RFC,v3,01/13] libahci: Allow drivers to override start_engine

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Submitter Hans de Goede
Date Jan. 18, 2014, 11:48 p.m.
Message ID <1390088935-7193-2-git-send-email-hdegoede@redhat.com>
Download mbox | patch
Permalink /patch/312342/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Hans de Goede - Jan. 18, 2014, 11:48 p.m.
From: Oliver Schinagl <oliver@schinagl.nl>

Allwinner A10 and A20 ARM SoCs have an AHCI sata controller which needs a
special register to be poked before starting the DMA engine.

This register gets reset on an ahci_stop_engine call, so there is no other
place then ahci_start_engine where this poking can be done.

This commit allows drivers to override ahci_start_engine behavior for use by
the Allwinner AHCI driver (and potentially other drivers in the future).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/ata/ahci.h    | 2 ++
 drivers/ata/libahci.c | 6 ++++++
 2 files changed, 8 insertions(+)
Tejun Heo - Jan. 19, 2014, 4:46 a.m.
Hello, Hans.

On Sun, Jan 19, 2014 at 12:48:43AM +0100, Hans de Goede wrote:
>  void ahci_start_engine(struct ata_port *ap)
>  {
>  	void __iomem *port_mmio = ahci_port_base(ap);
> +	struct ahci_host_priv *hpriv = ap->host->private_data;
>  	u32 tmp;
>  
> +	if (hpriv->start_engine) {
> +		hpriv->start_engine(ap);
> +		return;
> +	}
> +

I'd much prefer if the driver always calls hpriv->start_engine() which
is initialized to the default callback during common init and then
overridden if necessary.

Thanks.
Hans de Goede - Jan. 19, 2014, 6:48 p.m.
Hi,

On 01/19/2014 05:46 AM, Tejun Heo wrote:
> Hello, Hans.
>
> On Sun, Jan 19, 2014 at 12:48:43AM +0100, Hans de Goede wrote:
>>   void ahci_start_engine(struct ata_port *ap)
>>   {
>>   	void __iomem *port_mmio = ahci_port_base(ap);
>> +	struct ahci_host_priv *hpriv = ap->host->private_data;
>>   	u32 tmp;
>>
>> +	if (hpriv->start_engine) {
>> +		hpriv->start_engine(ap);
>> +		return;
>> +	}
>> +
>
> I'd much prefer if the driver always calls hpriv->start_engine() which
> is initialized to the default callback during common init and then
> overridden if necessary.

This is a bit trouble some because ahci_start_engine is also exported,
so the patch would also need to fix all callers (and probably un-export
it). I can do this in the next revision in the patch-set if you want me
to, just explaining why I choose to do this the way I did.

Regards,

Hans
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Patch

diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 2289efd..8f60f33 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -323,6 +323,8 @@  struct ahci_host_priv {
 	u32			em_msg_type;	/* EM message type */
 	struct clk		*clk;		/* Only for platforms supporting clk */
 	void			*plat_data;	/* Other platform data */
+	/* Optional ahci_start_engine override */
+	void			(*start_engine)(struct ata_port *ap);
 };
 
 extern int ahci_ignore_sss;
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index c482f8c..f6eabbc 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -568,8 +568,14 @@  static int ahci_scr_write(struct ata_link *link, unsigned int sc_reg, u32 val)
 void ahci_start_engine(struct ata_port *ap)
 {
 	void __iomem *port_mmio = ahci_port_base(ap);
+	struct ahci_host_priv *hpriv = ap->host->private_data;
 	u32 tmp;
 
+	if (hpriv->start_engine) {
+		hpriv->start_engine(ap);
+		return;
+	}
+
 	/* start DMA */
 	tmp = readl(port_mmio + PORT_CMD);
 	tmp |= PORT_CMD_START;