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SubjectRe: [PATCH 0/2] PCI: dwc: convert remaining dbi read/writes to dw_pcie_readX_dbi/dw_pcie_writeX_dbi
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On 08/16/2017 12:39 AM, Bjorn Helgaas wrote:
> [+cc Kishon, Pratyush]
>
> On Fri, Jul 14, 2017 at 02:07:33PM +0200, Niklas Cassel wrote:
>> Since the introduction of the dw_pcie_readX_dbi/dw_pcie_writeX_dbi macros,
>> most dw_pcie_read(pci->dbi_base, ..)/dw_pcie_write(pci->dbi_base, ..) calls
>> have been converted to dw_pcie_readX_dbi/dw_pcie_writeX_dbi calls.
>> Convert the remaining calls.
>>
>> Niklas Cassel (2):
>> PCI: dwc: dra7xx: utilize dw_pcie_readX_dbi/dw_pcie_writeX_dbi macros
>> PCI: dwc: spear13xx: utilize dw_pcie_readX_dbi/dw_pcie_writeX_dbi
>> macros
>>
>> drivers/pci/dwc/pci-dra7xx.c | 14 ++++++--------
>> drivers/pci/dwc/pcie-spear13xx.c | 22 ++++++++++------------
>> 2 files changed, 16 insertions(+), 20 deletions(-)
>
> These patches are short, but obscure, e.g.,
>
> - dw_pcie_read(pci->dbi_base + exp_cap_off + PCI_EXP_LNKCAP, 4, &val);
> + val = dw_pcie_readl_dbi(pci, exp_cap_off + PCI_EXP_LNKCAP);
>
> The original call path was:
>
> dw_pcie_read(addr, ...)
> readl(addr)
>
> and we're replacing it with the much more complicated:
>
> dw_pcie_readl_dbi
> __dw_pcie_read_dbi
> if (pci->ops->read_dbi)
> return pci->ops->read_dbi(pci, base, reg, size)
> dw_pcie_read(base + reg, size, &val)
> readl
>
> This is not functionally equivalent (the new path uses ops->read_dbi
> if it's set), so the changelog should say something about why we need
> this change.
>
> Neither dra7xx nor spear13xx sets .read_dbi, so my guess is this
> doesn't actually fix anything that's broken and this is just for
> consistency.

Hello Bjorn,

It is just for consistency.

Sorry for my misleading cover letter.
It should have said: "For consistency, convert all
dw_pcie_read(pci->dbi_base, ..)/dw_pcie_write(pci->dbi_base, ..)
calls to use the dw_pcie_readX_dbi/dw_pcie_writeX_dbi macros".

It is true that dw_pcie_readX_dbi/dw_pcie_writeX_dbi will use
ops->read_dbi if it is set. However, if ops->read_dbi is set,
you will most likely want to use that function for reading the dbi.
Anyway, neither spear13xx nor dra7xx has ops->read_dbi set,
so these patches shouldn't change their current behavior.

Do you want me to resend these patches or would you prefer
to just drop them?

Best regards,
Niklas

>
> That's fine, but I'm confused because I looked for some of the
> previous conversions you mentioned but couldn't find any. I'm lost in
> a maze of twisty little passages.
>
> Bjorn
>

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