Re: [RFC][PATCH] PowerPC 4xx: ibm_newemac 440GX phy clock workaround.

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Thu, 2008-02-21 at 17:46 +0300, Valentine Barshak wrote:
> The PowerPC 440GX Taishan board fails to reset EMAC3 (reset timeout error)
> and because of that it can't find PHY chip. The older ibm_emac driver had
> a workaround for that: the EMAC_CLK_INTERNAL/EMAC_CLK_EXTERNAL macros which
> toggle the Ethernet Clock Select bit in the SDR0_MFR register. This patch
> does the same for "ibm,emac-440gx" compatible chips.

The main problem is that will force clock on -all- EMACs ... which can
be a problem as they can be in probe at the same time. Might be worth
also adding a global mutex around that block.

Also, would you mind having a look at the other workaround for the
similar bug ?

Cheers,
Ben.

> Signed-off-by: Valentine Barshak <vbarshak@ru.mvista.com>
> ---
>  drivers/net/ibm_newemac/core.c |   16 +++++++++++++++-
>  drivers/net/ibm_newemac/core.h |    8 ++++++--
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff -pruN linux-2.6.orig/drivers/net/ibm_newemac/core.c linux-2.6/drivers/net/ibm_newemac/core.c
> --- linux-2.6.orig/drivers/net/ibm_newemac/core.c	2008-02-21 16:45:36.000000000 +0300
> +++ linux-2.6/drivers/net/ibm_newemac/core.c	2008-02-21 17:21:21.000000000 +0300
> @@ -43,6 +43,8 @@
>  #include <asm/io.h>
>  #include <asm/dma.h>
>  #include <asm/uaccess.h>
> +#include <asm/dcr.h>
> +#include <asm/dcr-regs.h>
>  
>  #include "core.h"
>  
> @@ -2480,8 +2482,11 @@ static int __devinit emac_init_config(st
>  	}
>  
>  	/* Check EMAC version */
> -	if (of_device_is_compatible(np, "ibm,emac4"))
> +	if (of_device_is_compatible(np, "ibm,emac4")) {
>  		dev->features |= EMAC_FTR_EMAC4;
> +		if (of_device_is_compatible(np, "ibm,emac-440gx"))
> +			dev->features |= EMAC_FTR_440GX_PHY_CLK_FIX;
> +	}
>  
>  	/* Fixup some feature bits based on the device tree */
>  	if (of_get_property(np, "has-inverted-stacr-oc", NULL))
> @@ -2673,8 +2678,17 @@ static int __devinit emac_probe(struct o
>  	dev->stop_timeout = STOP_TIMEOUT_100;
>  	INIT_DELAYED_WORK(&dev->link_work, emac_link_timer);
>  
> +	/* Enable internal phy clock source */
> +	if (emac_has_feature(dev, EMAC_FTR_440GX_PHY_CLK_FIX))
> +		mtdcri(SDR0, SDR0_MFR, mfdcri(SDR0, SDR0_MFR) | SDR0_MFR_ECS);
> +
>  	/* Find PHY if any */
>  	err = emac_init_phy(dev);
> +
> +	/* Enable external phy clock source */
> +	if (emac_has_feature(dev, EMAC_FTR_440GX_PHY_CLK_FIX))
> +		mtdcri(SDR0, SDR0_MFR, mfdcri(SDR0, SDR0_MFR) & ~SDR0_MFR_ECS);
> +
>  	if (err != 0)
>  		goto err_detach_tah;
>  
> diff -pruN linux-2.6.orig/drivers/net/ibm_newemac/core.h linux-2.6/drivers/net/ibm_newemac/core.h
> --- linux-2.6.orig/drivers/net/ibm_newemac/core.h	2008-02-21 16:45:36.000000000 +0300
> +++ linux-2.6/drivers/net/ibm_newemac/core.h	2008-02-21 17:21:47.000000000 +0300
> @@ -301,6 +301,10 @@ struct emac_instance {
>   * Set if we have new type STACR with STAOPC
>   */
>  #define EMAC_FTR_HAS_NEW_STACR		0x00000040
> +/*
> + * Set if we need phy clock workaround for 440gx
> + */
> +#define EMAC_FTR_440GX_PHY_CLK_FIX	0x00000080
>  
> 
>  /* Right now, we don't quite handle the always/possible masks on the
> @@ -312,8 +316,8 @@ enum {
>  
>  	EMAC_FTRS_POSSIBLE	=
>  #ifdef CONFIG_IBM_NEW_EMAC_EMAC4
> -	    EMAC_FTR_EMAC4	| EMAC_FTR_HAS_NEW_STACR	|
> -	    EMAC_FTR_STACR_OC_INVERT	|
> +	    EMAC_FTR_EMAC4 | EMAC_FTR_HAS_NEW_STACR |
> +	    EMAC_FTR_STACR_OC_INVERT | EMAC_FTR_440GX_PHY_CLK_FIX |
>  #endif
>  #ifdef CONFIG_IBM_NEW_EMAC_TAH
>  	    EMAC_FTR_HAS_TAH	|