> -----Original Message----- > From: Wendy Liang [mailto:sunnyliangjy@xxxxxxxxx] > Sent: Wednesday, October 10, 2018 3:54 PM > To: Sudeep Holla <sudeep.holla@xxxxxxx> > Cc: Jiaying Liang <jliang@xxxxxxxxxx>; Jassi Brar <jassisinghbrar@xxxxxxxxx>; > Michal Simek <michals@xxxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; > Mark Rutland <mark.rutland@xxxxxxx>; Devicetree List > <devicetree@xxxxxxxxxxxxxxx>; Linux Kernel Mailing List <linux- > kernel@xxxxxxxxxxxxxxx>; linux-arm-kernel <linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx> > Subject: Re: [PATCH v4 2/2] dt-bindings: mailbox: Add Xilinx IPI Mailbox > > On Wed, Oct 10, 2018 at 2:59 AM Sudeep Holla <sudeep.holla@xxxxxxx> > wrote: > > > > On Wed, Oct 10, 2018 at 12:18:32AM -0700, Wendy Liang wrote: > > > Xilinx ZynqMP IPI(Inter Processor Interrupt) is a hardware block in > > > ZynqMP SoC used for the communication between various processor > > > systems. > > > > > > Signed-off-by: Wendy Liang <wendy.liang@xxxxxxxxxx> > > > > [...] > > > > > +Optional properties: > > > +-------------------- > > > +- method: The method of accessing the IPI agent registers. > > > + Permitted values are: "smc" and "hvc". Default is > > > + "smc". > > > > You are mixing the hardware messaging based mailbox and the software > > "smc/hvc" based mailbox together here. Please keep them separated. > > IIUC smc/hvc based mailcox is used for "tx" or too keep it simple in > > one direction and hardware based is used for "rx" or the other > > direction for communication. > > > Hi Sudeep, > > Thanks for your comments. > > The IPI hardware block has both buffers and registers. The hardware block > has dedicated buffers for each mailboxes, and thus, in the implementation, > we directly access the buffers from IPI driver. However, the controller > registers are shared between mailboxes in the hardware, as the ATF will also > access the registers, we need to use SMC/HVC to access the registers (control > or ISR). And the SMC/HVC here is for the register access. > > I am not clear on smc/hvc based mailbox is used for tx, and hardware based > is used for "rx". As for both TX and RX, we need to write/read the registers > (through SMC) and write/read the buffers provided by the IPI hardware block > directly. [Wendy] Hi Sudeep, The SMC/HVC is for hardware registers access as but not sending messages. Do you have further comments or are you fine with the explanation? Thanks, Wendy > > Thanks, > Wendy > > > You *should not* mix them as single unit. Also lots of other vendor > > need SMC/HVC based mailbox. So make it generic and keep it separate. > > > > -- > > Regards, > > Sudeep
