[PATCH] mvme147: use correct order of ram pages

[PATCH] mvme147: use correct order of ram pages

[Amos Kong]

16K is 2^2 * PAGE_SIZE, so the page order should be 2, not 3.

This patch uses get_order() to get correct order, and fixes
one typo in comment.

Signed-off-by: Amos Kong <akong@redhat.com>
---
This patch wasn't built. Geert, can you help to test it?
I don't know if it needs a head file by using get_order().
---
 drivers/net/ethernet/amd/mvme147.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/amd/mvme147.c b/drivers/net/ethernet/amd/mvme147.c
index 0e8399d..4e98bf8 100644
--- a/drivers/net/ethernet/amd/mvme147.c
+++ b/drivers/net/ethernet/amd/mvme147.c
@@ -26,10 +26,11 @@
 #include <asm/pgtable.h>
 #include <asm/mvme147hw.h>
 
-/* We have 16834 bytes of RAM for the init block and buffers. This places
+/* We have 16384 bytes of RAM for the init block and buffers. This places
  * an upper limit on the number of buffers we can use. NetBSD uses 8 Rx
  * buffers and 2 Tx buffers.
  */
+#define M147LANCE_RAM_SIZE   16384 /* 16K */
 #define LANCE_LOG_TX_BUFFERS 1
 #define LANCE_LOG_RX_BUFFERS 3
 
@@ -111,7 +112,7 @@ struct net_device * __init mvme147lance_probe(int unit)
 	       dev->dev_addr);
 
 	lp = netdev_priv(dev);
-	lp->ram = __get_dma_pages(GFP_ATOMIC, 3);	/* 16K */
+	lp->ram = __get_dma_pages(GFP_ATOMIC, get_order(M147LANCE_RAM_SIZE));
 	if (!lp->ram) {
 		printk("%s: No memory for LANCE buffers\n", dev->name);
 		free_netdev(dev);
@@ -134,7 +135,7 @@ struct net_device * __init mvme147lance_probe(int unit)
 
 	err = register_netdev(dev);
 	if (err) {
-		free_pages(lp->ram, 3);
+		free_pages(lp->ram, get_order(M147LANCE_RAM_SIZE));
 		free_netdev(dev);
 		return ERR_PTR(err);
 	}
@@ -193,7 +194,7 @@ void __exit cleanup_module(void)
 {
 	struct m147lance_private *lp = netdev_priv(dev_mvme147_lance);
 	unregister_netdev(dev_mvme147_lance);
-	free_pages(lp->ram, 3);
+	free_pages(lp->ram, get_order(M147LANCE_RAM_SIZE));
 	free_netdev(dev_mvme147_lance);
 }
 
-- 
1.9.0

Re: [PATCH] mvme147: use correct order of ram pages

[Geert Uytterhoeven]

Hi Amos,

On Wed, May 28, 2014 at 6:07 AM, Amos Kong <akong@redhat.com> wrote:
> 16K is 2^2 * PAGE_SIZE, so the page order should be 2, not 3.
>
> This patch uses get_order() to get correct order, and fixes
> one typo in comment.

Thanks for your patch!

> Signed-off-by: Amos Kong <akong@redhat.com>
> ---
> This patch wasn't built. Geert, can you help to test it?
> I don't know if it needs a head file by using get_order().

It builds fine. The get_order() is nicely expanded to "2" in the assembler
output.

Now, I'd like to get some feedback from the MVME hackers first.
Perhaps the comment was wrong?

> -/* We have 16834 bytes of RAM for the init block and buffers. This places
> +/* We have 16384 bytes of RAM for the init block and buffers. This places
>   * an upper limit on the number of buffers we can use. NetBSD uses 8 Rx
>   * buffers and 2 Tx buffers.
>   */
> +#define M147LANCE_RAM_SIZE   16384 /* 16K */
>  #define LANCE_LOG_TX_BUFFERS 1
>  #define LANCE_LOG_RX_BUFFERS 3

BTW,I also find it fishy why the driver uses only 1+3 buffers, since more
RAM is available.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] mvme147: use correct order of ram pages

[Andreas Schwab]

Geert Uytterhoeven <geert@linux-m68k.org> writes:

>> -/* We have 16834 bytes of RAM for the init block and buffers. This places
>> +/* We have 16384 bytes of RAM for the init block and buffers. This places
>>   * an upper limit on the number of buffers we can use. NetBSD uses 8 Rx
>>   * buffers and 2 Tx buffers.
>>   */
>> +#define M147LANCE_RAM_SIZE   16384 /* 16K */
>>  #define LANCE_LOG_TX_BUFFERS 1
>>  #define LANCE_LOG_RX_BUFFERS 3
>
> BTW,I also find it fishy why the driver uses only 1+3 buffers, since more
> RAM is available.

It's 2^1+2^3.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [PATCH] mvme147: use correct order of ram pages

[Amos Kong]

On Wed, May 28, 2014 at 11:39:20AM +0200, Andreas Schwab wrote:
> Geert Uytterhoeven <geert@linux-m68k.org> writes:
> 
> >> -/* We have 16834 bytes of RAM for the init block and buffers. This places
> >> +/* We have 16384 bytes of RAM for the init block and buffers. This places
> >>   * an upper limit on the number of buffers we can use. NetBSD uses 8 Rx
> >>   * buffers and 2 Tx buffers.
> >>   */
> >> +#define M147LANCE_RAM_SIZE   16384 /* 16K */
> >>  #define LANCE_LOG_TX_BUFFERS 1
> >>  #define LANCE_LOG_RX_BUFFERS 3
> >

#define TX_RING_SIZE            (1 << LANCE_LOG_TX_BUFFERS)
#define RX_RING_SIZE            (1 << LANCE_LOG_RX_BUFFERS)

> > BTW,I also find it fishy why the driver uses only 1+3 buffers, since more
> > RAM is available.
> 
> It's 2^1+2^3.

tx & rx bufs aren't 2^1 + 2^3 = 10 pages. 

Rx buffers and Tx buffers are included in 'struct lance_init_block'

   volatile char tx_buf[TX_RING_SIZE][TX_BUFF_SIZE];
   volatile char rx_buf[RX_RING_SIZE][RX_BUFF_SIZE];

   volatile char tx_buf[2][1544];
   volatile char rx_buf[8][1544];

   RX_BUFF_SIZE = TX_BUFF_SIZE = 1554
   So tx_buf takes 1544 * 2 bytes, rx_buf takes 1544 * 8 bytes
        
In drivers/net/ethernet/amd/mvme147.c:
=====================================
  lp->lance.init_block = (struct lance_init_block *)(lp->ram); /* CPU addr */
  lp->lance.lance_init_block = (struct lance_init_block*)(lp->ram); /* LANCE addr of same RAM */

init_block and lance_init_block are set same address

In drivers/net/ethernet/amd/a2065.c:
===================================
  priv->init_block = (struct lance_init_block *)dev->mem_start;
  priv->lance_init_block = (struct lance_init_block *)A2065_RAM;

  The ram size (A2065_RAM_SIZE) is 0x8000 -> 8 pages -> order is 3

It seems original 3 is a right order, we need to fix the comments.
it's 2^3 * 4k = 32K = 32768 bytes.

But in drivers/net/ethernet/amd/hplance.c:
=========================================
  #define HPLANCE_MEMOFF 0x8000 /* struct lance_init_block */
  lp->lance.init_block = (struct lance_init_block *)(va + HPLANCE_MEMOFF); /* CPU addr */
                                                          ^^^^ it skips 0x8000, that is for HPLANCE
  lp->lance.lance_init_block = NULL; /* LANCE addr of same RAM */

  We need 2 * 32k for lp->ram?

 
> Andreas.
> 
> -- 
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
> "And now for something completely different."
> --
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-- 
			Amos.