Re: pci-exynos.c phy_init() usage

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hi,

On 24.06.2022 20:07, Krzysztof Kozlowski wrote:
> On 24/06/2022 19:35, Bjorn Helgaas wrote:
>> In exynos_pcie_host_init() [1], we call:
>>
>>    phy_reset(ep->phy);
>>    phy_power_on(ep->phy);
>>    phy_init(ep->phy);
>>
>> The phy_init() function comment [2] says it must be called before
>> phy_power_on().  Is exynos doing this backwards?
> Looks like. I don't have Exynos hardware with a PCI, so cannot
> test/fix/verify.
>
> Luckily for Exynos ;-) it's not alone in this pattern:
> drivers/net/ethernet/marvell/sky2.c
> drivers/usb/dwc2/platform.c

I've checked that on the real hardware. Swapping the order of 
phy_power_on and phy_init breaks driver operation.

However pci-exynos is the only driver that uses the phy-exynos-pcie, so 
we can simply swap the content of the init and power_on in the phy 
driver to adjust the code to the right order. power_on/init and 
exit/power_off are also called one after the other in pci-exynos, 
without any activity between them, so we can also simply move all 
operation to one pair of the callback, like power_on/off.

Krzysztof, which solution would you prefer?

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland