Does it mean that pci is supposed be always 64 bit wide?
And there is no option to have just 32bit values.

I certainly believe that all PCIe (not PCI) transfers are
nominally multiples of 64bit data.
There are (effectively) 8 byte-lane enables to allow partial word
transfers (I'm not sure whether disjoint subwords are valid).

Some PCIe slave->32bit bus bridges always do two slave cycles.
Even though, for a 32bit word transfer, one of them ends up having
no byte enables asserted.

	David