Subject: Re: [PATCH net] xgene: Don't fail probe, if there is no clk resource
 for SGMII interfaces
To: Tom Bogendoerfer <tsbogend@alpha.franken.de>
Cc: isubramanian@apm.com, kchudgar@apm.com, qnguyen@apm.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20170713092144.31751508094@solo.franken.de>
 <22ee6284-7b23-7664-d6cf-23687f09a3be@redhat.com>
 <20170727213915.GA4902@alpha.franken.de>
 <1b3391f2-2fae-2a9a-719d-3f8358e39c71@redhat.com>
 <20170728142318.GA20368@alpha.franken.de>
From: Laura Abbott <labbott@redhat.com>
Message-ID: <41cdb992-8387-80db-5d48-4d16c85cb14a@redhat.com>
Date: Fri, 28 Jul 2017 09:42:21 -0700
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On 07/28/2017 07:23 AM, Tom Bogendoerfer wrote:
> On Thu, Jul 27, 2017 at 03:39:58PM -0700, Laura Abbott wrote:
>> I don't know the intricacies of the Mustang hardware but external
>> aborts have been a symptom of missing clocks on other hardware.
> 
> you are right, it's a missing clock. For SGMII ports the driver
> doesn't really use the clock source other then doing the one
> devm_clk_get(), but this is enough to get the clock going.
> 
> Below patch fixes the crash and brings back the second SGMII port
> (even without a clock source in device tree, I guess it uses clock
> from first port).  From a correctness standpoint there should probably 
> be a clk_prepare_enable(), if port is SGMII.
> 
> Could you test the patch ? If it works, I'll submit it.
> 
> Thomas.
> 
> diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> index 86058a9f3417..1d307f2def2d 100644
> --- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> +++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> @@ -1785,9 +1785,9 @@ static int xgene_enet_get_resources(struct xgene_enet_pdata *pdata)
>  
>  	xgene_enet_gpiod_get(pdata);
>  
> -	if (pdata->phy_mode != PHY_INTERFACE_MODE_SGMII) {
> -		pdata->clk = devm_clk_get(&pdev->dev, NULL);
> -		if (IS_ERR(pdata->clk)) {
> +	pdata->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(pdata->clk)) {
> +		if (pdata->phy_mode != PHY_INTERFACE_MODE_SGMII) {
>  			/* Abort if the clock is defined but couldn't be
>  			 * retrived. Always abort if the clock is missing on
>  			 * DT system as the driver can't cope with this case.
> 


Yes, this works. You can add my Tested-by.

Thanks,
Laura