Re: [Pasemi-linux] [patch 1/6] pasemi_mac: Move RX/TX section enablement to dma_lib

On Tue, Feb 26, 2008 at 08:14:20AM -0600, Olof Johansson wrote:

Hi,

On Tue, Feb 26, 2008 at 10:46:06PM +1100, Michael Ellerman wrote:

quoted

On Wed, 2008-02-20 at 20:57 -0600, Olof Johansson wrote:

quoted

+	i = 1000;
+	pasemi_write_dma_reg(PAS_DMA_COM_RXCMD, 0);
+	while ((i > 0) && (pasemi_read_dma_reg(PAS_DMA_COM_RXSTA) & 1))
+		i--;
+	if (i < 0)
+		printk(KERN_INFO "Warning: Could not disable RX section\n");
+
+	i = 1000;
+	pasemi_write_dma_reg(PAS_DMA_COM_TXCMD, 0);
+	while ((i > 0) && (pasemi_read_dma_reg(PAS_DMA_COM_TXSTA) & 1))
+		i--;

This kind of caught my eye, is it still going to work when the next core
is twice as fast?

Actually, I added the variable right before posting, I used to have an
infinite loop there while testing the patch. I've never seen it do more
than a few rounds, so I'm not that worried.

We already have a similar loop in the channel shutdown code, but it runs
a bit longer. I might bring that over instead. Thanks for pointing it
out.

FYI; I've commited in this change, rest of the patch is identical.

diff --git a/arch/powerpc/platforms/pasemi/dma_lib.c b/arch/powerpc/platforms/pasemi/dma_lib.c
index c529d8d..48cb7c9 100644
--- a/arch/powerpc/platforms/pasemi/dma_lib.c
+++ b/arch/powerpc/platforms/pasemi/dma_lib.c

@@ -17,6 +17,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */
 
+#include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/pci.h>

@@ -410,6 +411,7 @@ int pasemi_dma_init(void)
 	struct resource res;
 	struct device_node *dn;
 	int i, intf, err = 0;
+	unsigned long timeout;
 	u32 tmp;
 
 	if (!machine_is(pasemi))

@@ -478,6 +480,34 @@ int pasemi_dma_init(void)
 	for (i = 0; i < MAX_RXCH; i++)
 		__set_bit(i, rxch_free);
 
+	timeout = jiffies + HZ;
+	pasemi_write_dma_reg(PAS_DMA_COM_RXCMD, 0);
+	while (pasemi_read_dma_reg(PAS_DMA_COM_RXSTA) & 1) {
+		if (time_after(jiffies, timeout)) {
+			pr_warning("Warning: Could not disable RX section\n");
+			break;
+		}
+	}
+
+	timeout = jiffies + HZ;
+	pasemi_write_dma_reg(PAS_DMA_COM_TXCMD, 0);
+	while (pasemi_read_dma_reg(PAS_DMA_COM_TXSTA) & 1) {
+		if (time_after(jiffies, timeout)) {
+			pr_warning("Warning: Could not disable TX section\n");
+			break;
+		}
+	}