On Wed, Sep 6, 2017 at 8:27 AM, Kuppuswamy, Sathyanarayanan <sathyaosid@xxxxxxxxx> wrote: > On 9/5/2017 12:38 AM, Lee Jones wrote: >> On Sat, 02 Sep 2017, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote: >> I'm a bit concerned by the API. > > This is not a new change. Even before refactoring this driver, we have been > using u32 bit variable to pass the DPTR and SPTR address. >> >> Any reason why you're not using >> pointers for addresses? > > I think the main reason is, this is the expected format defined by SCU/PMC > spec. According to the spec document, SPTR and DPTR registers are used to > program the 32 bit SRAM address from which the PMC/SCU firmware can > read/write the data of an IPC command. if we are not using SPTR or DPTR, we > need to leave the value at zero. It's an effect, the cause is that the system controllers which are used in Intel SoCs are 32-bit microprocessors and they can't address more. That's why SRAM is placed in 32-bit address space. And thus, the SCU protocol defines fixed width parameters for addresses. So, it means we can't use any address outside of 4G space, iow 32-bit wide. >> pointers, you should be using NULL, instead of 0. -- With Best Regards, Andy Shevchenko
