Re: [RESEND PATCH v3 4/7] PCI: dwc: all: Modify dbi accessors to take dbi_base as argument

Kishon Vijay Abraham I
2017-03-10T13:00:10Z

Hi Niklas,

On Friday 10 March 2017 06:01 PM, Niklas Cassel wrote:
> On 03/10/2017 12:36 PM, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On Thursday 09 March 2017 08:35 PM, Niklas Cassel wrote:
>>>
>>> On 03/09/2017 03:48 PM, Niklas Cassel wrote:
>>>> On 03/09/2017 07:39 AM, Kishon Vijay Abraham I wrote:
>>>>> dwc has 2 dbi address space labeled dbics and dbics2. The existing
>>>>> helper to access dbi address space can access only dbics. However
>>>>> dbics2 has to be accessed for programming the BAR registers in the
>>>>> case of EP mode. This is in preparation for adding EP mode support
>>>>> to dwc driver.
>>>> Hello Kishon
>>>>
>>>> I don't really like the idea of adding an extra argument to every existing read/write.
>>>> Will not a read/write using dbi2 be quite uncommon compared to a read/write
>>>> using dbi?
>>>>
>>>> How about something like this:
>>>>
>>>> void __dw_pcie_writel(struct dw_pcie *pci, void __iomem *base, u32 reg, u32 val)
>>>> {
>>>> if (pci->ops->writel_dbi)
>>>> pci->ops->writel_dbi(pci, base, reg, val);
>>>> else
>>>> writel(val, base + reg);
>>>> }
>>>>
>>>> #define dw_pcie_writel_dbi(pci, reg, val) __dw_pcie_writel(pci, pci->dbi_base, reg, val)
>>>> #define dw_pcie_writel_dbi2(pci, reg, val) __dw_pcie_writel(pci, pci->dbi_base2, reg, val)
>>> Perhaps make dw_pcie_writel_dbi2 a function rather than a define,
>>> so we can return an error if pci->dbi_base2 == NULL.
>> Should we return an error? We don't return error for dbi_base either. I think
>> it should be sufficient to return errors while populating dbi_base or
>> dbi_base2. Otherwise it's a bug and should result in abort. Joao?
>
> Sorry for previous empty email.
>
>
> What I meant to write:
>
> Right now we do error checking for dbi_base in platform specific code
> and in pcie-designware-host.c:dw_pcie_host_init.

it's been done in dw_pcie_host_init not as an error checking but since it's
*optional* for certain platforms to populate dbi_base (i.e where dbi_base is
mapped to configuration space), host_init takes care of assigning dbi_base to
configuration space address.

Thanks
Kishon