From: Andrew Morton <akpm@linux-foundation•org>
To: Risto Suominen <risto.suominen@gmail•com>
Cc: jgarzik@pobox•com, linux-kernel@vger•kernel.org,
netdev@vger•kernel.org,
Grant Grundler <grundler@parisc-linux•org>
Subject: Re: [PATCH 002/002] de2104x: support for systems lacking cache coherence
Date: Mon, 9 Feb 2009 17:01:20 -0800 [thread overview]
Message-ID: <20090209170120.85e192be.akpm@linux-foundation.org> (raw)
In-Reply-To: <46e1c7760902071330i5362fe4fvd99fc7075fc666d3@mail.gmail.com>
(cc netdev, and maintainer)
On Sat, 7 Feb 2009 23:30:40 +0200
Risto Suominen <risto.suominen@gmail•com> wrote:
> 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
Please prefer to prepare patches in `patch -p1' form:
--- a/drivers/net/tulip/Kconfig
+++ a/drivers/net/tulip/Kconfig
> @@ -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
I think CONFIG_DE2104X_DSL is always defined if this driver is being
compiled. So the Kconfig `default' should suffice here? In which case
we can do
#define DSL CONFIG_DE2104X_DSL
and leave it at that.
> #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),
In which case we can do away with DSL everywhere and just use
CONFIG_DE2104X_DSL here.
But really, we shouldn't do this at configuration time at all. It
would be much better to do it at runtime, via a module parameter.
And it would be much^2 better to do it automatically, based upon the
chip probing information or whatever. That's probably hard.
> /* 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
> };
Can remove the ifdefs here. A zero-length array is OK, and will
consume zero space.
next prev parent reply other threads:[~2009-02-10 1:02 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <46e1c7760902071330i5362fe4fvd99fc7075fc666d3@mail.gmail.com>
2009-02-09 7:27 ` Fwd: [PATCH 002/002] de2104x: support for systems lacking cache coherence Risto Suominen
2009-02-09 7:45 ` David Miller
2009-02-09 8:22 ` Risto Suominen
2009-02-09 8:29 ` David Miller
2009-02-09 8:35 ` Risto Suominen
2009-02-09 16:58 ` Krzysztof Halasa
2009-02-09 19:22 ` Risto Suominen
2009-02-09 22:51 ` David Miller
2009-02-10 1:45 ` Krzysztof Halasa
2009-02-10 1:50 ` David Miller
2009-02-10 23:21 ` David Miller
2009-02-11 12:18 ` Risto Suominen
2009-02-11 12:31 ` Risto Suominen
2009-02-11 21:39 ` David Miller
2009-02-13 3:42 ` Benjamin Herrenschmidt
2009-02-10 1:01 ` Andrew Morton [this message]
2009-02-10 1:07 ` David Miller
2009-02-10 7:16 ` Risto Suominen
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