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Subject[PATCH 002/002] de2104x: support for systems lacking cache coherence
From
Add a configurable Descriptor Skip Length for systems that lack cache coherence.

Signed-off-by: Risto Suominen <Risto.Suominen@gmail.com>
---
The testing is done on kernel version 2.6.18.
--- drivers/net/tulip/Kconfig.org 2006-09-20 06:42:06.000000000 +0300
+++ drivers/net/tulip/Kconfig 2009-02-07 20:48:17.000000000 +0200
@@ -27,6 +27,18 @@ config DE2104X
To compile this driver as a module, choose M here. The module will
be called de2104x.

+config DE2104X_DSL
+ int "Descriptor Skip Length in 32 bit longwords"
+ depends on DE2104X
+ range 0 31
+ default 0
+ help
+ Setting this value allows to align ring buffer descriptors into their
+ own cache lines. Value of 4 corresponds to the typical 32 byte line
+ (the descriptor is 16 bytes). This is necessary on systems that lack
+ cache coherence, an example is PowerMac 5500. Otherwise 0 is safe.
+ Default is 0, and range is 0 to 31.
+
config TULIP
tristate "DECchip Tulip (dc2114x) PCI support"
depends on PCI
--- drivers/net/tulip/de2104x.c.org 2006-09-20 06:42:06.000000000 +0300
+++ drivers/net/tulip/de2104x.c 2009-02-07 15:04:04.000000000 +0200
@@ -82,6 +82,13 @@ MODULE_PARM_DESC (rx_copybreak, "de2104x
NETIF_MSG_RX_ERR | \
NETIF_MSG_TX_ERR)

+/* Descriptor skip length in 32 bit longwords. */
+#ifndef CONFIG_DE2104X_DSL
+#define DSL 0
+#else
+#define DSL CONFIG_DE2104X_DSL
+#endif
+
#define DE_RX_RING_SIZE 64
#define DE_TX_RING_SIZE 64
#define DE_RING_BYTES \
@@ -153,6 +160,7 @@ enum {
CmdReset = (1 << 0),
CacheAlign16 = 0x00008000,
BurstLen4 = 0x00000400,
+ DescSkipLen = (DSL << 2),

/* Rx/TxPoll bits */
NormalTxPoll = (1 << 0),
@@ -246,7 +254,7 @@ static const u32 de_intr_mask =
* Set the programmable burst length to 4 longwords for all:
* DMA errors result without these values. Cache align 16 long.
*/
-static const u32 de_bus_mode = CacheAlign16 | BurstLen4;
+static const u32 de_bus_mode = CacheAlign16 | BurstLen4 | DescSkipLen;

struct de_srom_media_block {
u8 opts;
@@ -266,6 +274,9 @@ struct de_desc {
__le32 opts2;
__le32 addr1;
__le32 addr2;
+#if DSL
+ __le32 skip[DSL];
+#endif
};

struct media_info {Add a configurable Descriptor Skip Length for systems that lack cache coherence.

Signed-off-by: Risto Suominen <Risto.Suominen@gmail.com>
---
The testing is done on kernel version 2.6.18.
--- drivers/net/tulip/Kconfig.org 2006-09-20 06:42:06.000000000 +0300
+++ drivers/net/tulip/Kconfig 2009-02-07 20:48:17.000000000 +0200
@@ -27,6 +27,18 @@ config DE2104X
To compile this driver as a module, choose M here. The module will
be called de2104x.

+config DE2104X_DSL
+ int "Descriptor Skip Length in 32 bit longwords"
+ depends on DE2104X
+ range 0 31
+ default 0
+ help
+ Setting this value allows to align ring buffer descriptors into their
+ own cache lines. Value of 4 corresponds to the typical 32 byte line
+ (the descriptor is 16 bytes). This is necessary on systems that lack
+ cache coherence, an example is PowerMac 5500. Otherwise 0 is safe.
+ Default is 0, and range is 0 to 31.
+
config TULIP
tristate "DECchip Tulip (dc2114x) PCI support"
depends on PCI
--- drivers/net/tulip/de2104x.c.org 2006-09-20 06:42:06.000000000 +0300
+++ drivers/net/tulip/de2104x.c 2009-02-07 15:04:04.000000000 +0200
@@ -82,6 +82,13 @@ MODULE_PARM_DESC (rx_copybreak, "de2104x
NETIF_MSG_RX_ERR | \
NETIF_MSG_TX_ERR)

+/* Descriptor skip length in 32 bit longwords. */
+#ifndef CONFIG_DE2104X_DSL
+#define DSL 0
+#else
+#define DSL CONFIG_DE2104X_DSL
+#endif
+
#define DE_RX_RING_SIZE 64
#define DE_TX_RING_SIZE 64
#define DE_RING_BYTES \
@@ -153,6 +160,7 @@ enum {
CmdReset = (1 << 0),
CacheAlign16 = 0x00008000,
BurstLen4 = 0x00000400,
+ DescSkipLen = (DSL << 2),

/* Rx/TxPoll bits */
NormalTxPoll = (1 << 0),
@@ -246,7 +254,7 @@ static const u32 de_intr_mask =
* Set the programmable burst length to 4 longwords for all:
* DMA errors result without these values. Cache align 16 long.
*/
-static const u32 de_bus_mode = CacheAlign16 | BurstLen4;
+static const u32 de_bus_mode = CacheAlign16 | BurstLen4 | DescSkipLen;

struct de_srom_media_block {
u8 opts;
@@ -266,6 +274,9 @@ struct de_desc {
__le32 opts2;
__le32 addr1;
__le32 addr2;
+#if DSL
+ __le32 skip[DSL];
+#endif
};

struct media_info {
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