linux-kernel - Re: [PATCH 2/3] PCI: host: pcie-designware: add support for suspend and resume

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Date:	Thu, 23 Jul 2015 18:20:31 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Jingoo Han <jingoohan1@...il.com>
CC:	"'Bjorn Helgaas'" <bhelgaas@...gle.com>,
	"'Pratyush Anand'" <pratyush.anand@...il.com>,
	<linux-omap@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <nsekhar@...com>
Subject: Re: [PATCH 2/3] PCI: host: pcie-designware: add support for suspend
 and resume

Hi,

On Sunday 12 July 2015 04:01 PM, Jingoo Han wrote:
> On Friday, July 03, 2015 8:04 PM, Kishon Vijay Abraham I wrote:
>>
>> Certain platforms require MSE bit to be cleared to set the master
>> in standby mode. (In DRA7xx TRM_vE, section 24.9.4.5.2.2.1 PCIe
> 
> This patch is a work-around specific for DRA7xx chips?
> If so, please move this patch to 'pci-dra7xx.c'.
> I don't want to include chip-specific codes, because
> 'pcie-designware.c' is designed for including common codes.

Alright. Will change it that way in the next version.

Thanks
Kishon
> 
> Best regards,
> Jingoo Han
> 
>> Controller Master Standby Behavior advises to use the clearing
>> of the local MSE bit to set the master in standby. Without this
>> some of the clocks do not idle).
>>
>> Cleared the MSE bit on suspend and enabled it back on resume.
>> This is required to get suspend/resume working.
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
>> Signed-off-by: Sekhar Nori <nsekhar@...com>
>> ---
>>  drivers/pci/host/pcie-designware.c |   20 ++++++++++++++++++++
>>  drivers/pci/host/pcie-designware.h |    2 ++
>>  2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
>> index 69486be..cfb2bd6 100644
>> --- a/drivers/pci/host/pcie-designware.c
>> +++ b/drivers/pci/host/pcie-designware.c
>> @@ -811,6 +811,26 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
>>  	dw_pcie_writel_rc(pp, val, PCI_COMMAND);
>>  }
>>
>> +void dw_pcie_suspend_rc(struct pcie_port *pp)
>> +{
>> +	u32 val;
>> +
>> +	/* clear MSE */
>> +	dw_pcie_readl_rc(pp, PCI_COMMAND, &val);
>> +	val &= ~PCI_COMMAND_MEMORY;
>> +	dw_pcie_writel_rc(pp, val, PCI_COMMAND);
>> +}
>> +
>> +void dw_pcie_resume_rc(struct pcie_port *pp)
>> +{
>> +	u32 val;
>> +
>> +	/* set MSE */
>> +	dw_pcie_readl_rc(pp, PCI_COMMAND, &val);
>> +	val |= PCI_COMMAND_MEMORY;
>> +	dw_pcie_writel_rc(pp, val, PCI_COMMAND);
>> +}
>> +
>>  MODULE_AUTHOR("Jingoo Han <jg1.han@...sung.com>");
>>  MODULE_DESCRIPTION("Designware PCIe host controller driver");
>>  MODULE_LICENSE("GPL v2");
>> diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
>> index d0bbd27..0df2dfa 100644
>> --- a/drivers/pci/host/pcie-designware.h
>> +++ b/drivers/pci/host/pcie-designware.h
>> @@ -83,5 +83,7 @@ void dw_pcie_msi_init(struct pcie_port *pp);
>>  int dw_pcie_link_up(struct pcie_port *pp);
>>  void dw_pcie_setup_rc(struct pcie_port *pp);
>>  int dw_pcie_host_init(struct pcie_port *pp);
>> +void dw_pcie_suspend_rc(struct pcie_port *pp);
>> +void dw_pcie_resume_rc(struct pcie_port *pp);
>>
>>  #endif /* _PCIE_DESIGNWARE_H */
>> --
>> 1.7.9.5
> 
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