On Tue, Apr 30, 2019 at 09:24:29PM +0000, Vadim Pasternak wrote: > > > > -----Original Message----- > > From: Asmaa Mnebhi <as...@mellanox.com> > > Sent: Tuesday, April 30, 2019 8:59 PM > > To: miny...@acm.org; w...@the-dreams.de; Vadim Pasternak > > <vad...@mellanox.com>; Michael Shych <michae...@mellanox.com> > > Cc: Asmaa Mnebhi <as...@mellanox.com>; linux-kernel@vger.kernel.org; > > linux-...@vger.kernel.org > > Subject: [PATCH v4 0/1] Add support for IPMB driver > > > > Thank you for your feedback Vadim. I have addressed your comments. > > Hi Asmaa, > > Thank you for your comments and added doc. > > > > > 1) You are correct. This driver is not specific to Mellanox so I have > > removed the > > Mellanox attribute. > > > > 2) I have added a documentation file called IPMB.txt which explains how this > > module works and how it should be instantiated. It is very similar to the > > existing > > linux i2c-slave-eeprom module. > > > > The HW for my testing works as follows: > > A BMC is connected to a Satellite MC via I2C (I2C is equivalent to IPMB). > > The > > BMC initiates the IPMB requests and sends them via I2C. > > Obviously the BMC needs its own driver to do this which I haven't included > > in this > > code. We have no intent of upstreaming that at the moment. > > I believe you are going to do it at some point, right?
This is a little confusing to me. Why wouldn't you use the same driver on the BMC? IIRC, the IPMB protocol is symmetric at this level. -corey > > > This ipmb-dev-int driver is to be loaded and instantiated on the Satellite > > MC to > > be able to receive IPMB requests. These IPMB request messages will be picked > > up by a user space program such (in my case it is OpenIPMI) to handle the > > request and generate a response. > > The response will be then passed from the user program back to kernel space. > > Then this driver would send that response back to the BMC. > > > > 3) You asked the following: > > > > "Is it expected to be zero in vaid case?" > > The 8 least significant bits of the sum is always expected to be 0 in the > > case > > where the checksum is valid. I have added a comment for clarifications. > > > > > > "why do you need this cast?" > > buf[++ipmb_dev_p->msg_idx]=(u8)(client->addr<<1) > > This is because client->addr is of type unsigned short which is > > 2 bytes so it is safer to typecast it to u8 (u8* buf) > > Better, if you can avoid cast. > Would compiler warn if you use for example > rol16(client->addr, 1) & GENMASK(7, 0); > or something like it? > > > > > > "It could be only single ipmb-dev within the system? Couldn't it be few, > > like > > master/slave for example?" > > My understanding of your question is that: what if we have multiple > > instances of > > ipmb-dev-int, that we register it under different addresses? > > This driver only works as a slave so it will only be instantiated once on > > the > > Satellite MC under one slave address. > > I mentioned some config like: > BMC1 (master) -- busA --| > Satellite > BMC2 (standby) -- busB --| > > Since this is not Mellanox specific driver, maybe it would be good to support > multiple instances of it. I second this. Especially if it's on a BMC, you can expect to have multiple IPMBs. -corey > > > > > Asmaa Mnebhi (1): > > Add support for IPMB driver > > > > Documentation/IPMB.txt | 53 ++++++ > > drivers/char/ipmi/Kconfig | 8 + > > drivers/char/ipmi/Makefile | 1 + > > drivers/char/ipmi/ipmb_dev_int.c | 381 > > +++++++++++++++++++++++++++++++++++++++ > > 4 files changed, 443 insertions(+) > > create mode 100644 Documentation/IPMB.txt create mode 100644 > > drivers/char/ipmi/ipmb_dev_int.c > > > > -- > > 2.1.2 >
