linux-kernel - Re: [PATCH 08/13] PCI: cadence: Use local management register to configure Vendor ID

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Date:   Thu, 19 Dec 2019 17:42:27 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Andrew Murray <andrew.murray@....com>
CC:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>, Tom Joseph <tjoseph@...ence.com>
Subject: Re: [PATCH 08/13] PCI: cadence: Use local management register to
 configure Vendor ID

+Tom

Hi,

On 17/12/19 6:12 pm, Andrew Murray wrote:
> On Mon, Dec 09, 2019 at 02:51:42PM +0530, Kishon Vijay Abraham I wrote:
>> PCI_VENDOR_ID in root port configuration space is read-only register
>> and writing to it will have no effect. Use local management register to
>> configure Vendor ID and Subsystem Vendor ID.
> 
> Is this a bug fix? Can you add a Fixes tag and make that clearer?

I think this might have worked in Cadence platform? Tom?

Thanks
Kishon

> 
> Thanks,
> 
> Andrew Murray
> 
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
>> ---
>>  drivers/pci/controller/cadence/pcie-cadence-host.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> index cf817be237af..afb2c96a6538 100644
>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> @@ -71,6 +71,7 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
>>  {
>>  	struct cdns_pcie *pcie = &rc->pcie;
>>  	u32 value, ctrl;
>> +	u32 id;
>>  
>>  	/*
>>  	 * Set the root complex BAR configuration register:
>> @@ -90,8 +91,12 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
>>  	cdns_pcie_writel(pcie, CDNS_PCIE_LM_RC_BAR_CFG, value);
>>  
>>  	/* Set root port configuration space */
>> -	if (rc->vendor_id != 0xffff)
>> -		cdns_pcie_rp_writew(pcie, PCI_VENDOR_ID, rc->vendor_id);
>> +	if (rc->vendor_id != 0xffff) {
>> +		id = CDNS_PCIE_LM_ID_VENDOR(rc->vendor_id) |
>> +			CDNS_PCIE_LM_ID_SUBSYS(rc->vendor_id);
>> +		cdns_pcie_writel(pcie, CDNS_PCIE_LM_ID, id);
>> +	}
>> +
>>  	if (rc->device_id != 0xffff)
>>  		cdns_pcie_rp_writew(pcie, PCI_DEVICE_ID, rc->device_id);
>>  
>> -- 
>> 2.17.1
>>