> -----Original Message----- > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx] > Sent: Friday 21 June 2019 15:16 > To: Dragan Cvetic <draganc@xxxxxxxxxx> > Cc: arnd@xxxxxxxx; Michal Simek <michals@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx; > mark.rutland@xxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Derek Kiernan <dkiernan@xxxxxxxxxx> > Subject: Re: [PATCH V7 00/11] misc: xilinx sd-fec drive > > On Tue, Jun 11, 2019 at 06:29:34PM +0100, Dragan Cvetic wrote: > > This patchset is adding the full Soft Decision Forward Error > > Correction (SD-FEC) driver implementation, driver DT binding and > > driver documentation. > > > > Forward Error Correction (FEC) codes such as Low Density Parity > > Check (LDPC) and turbo codes provide a means to control errors in > > data transmissions over unreliable or noisy communication > > channels. The SD-FEC Integrated Block is an optimized block for > > soft-decision decoding of these codes. Fixed turbo codes are > > supported directly, whereas custom and standardized LDPC codes > > are supported through the ability to specify the parity check > > matrix through an AXI4-Lite bus or using the optional programmable > > (PL)-based support logic. For the further information see > > https://www.xilinx.com/support/documentation/ip_documentation/ > > sd_fec/v1_1/pg256-sdfec-integrated-block.pdf > > > > This driver is a platform device driver which supports SDFEC16 > > (16nm) IP. SD-FEC driver supports LDPC decoding and encoding and > > Turbo code decoding. LDPC codes can be specified on > > a codeword-by-codeword basis, also a custom LDPC code can be used. > > > > The SD-FEC driver exposes a char device interface and supports > > file operations: open(), close(), poll() and ioctl(). The driver > > allows only one usage of the device, open() limits the number of > > driver instances. The driver also utilize Common Clock Framework > > (CCF). > > > > The control and monitoring is supported over ioctl system call. > > The features supported by ioctl(): > > - enable or disable data pipes to/from device > > - configure the FEC algorithm parameters > > - set the order of data > > - provide a control of a SDFEC bypass option > > - activates/deactivates SD-FEC > > - collect and provide statistical data > > - enable/disable interrupt mode > > Is there any userspace tool that talks to this device using these custom > ioctls yet? > Tools no, but could be the customer who is using the driver. > Doing a one-off ioctl api is always a risky thing, you are pretty much > just creating brand new system calls for one piece of hardware. > Why is that wrong and what is the risk? What would you propose? Definitely, I have to read about this. > Anyway, I took the first 3 patches here because they looked sane. and > stopped when I ran into the ioctl problem... > Thanks for these 3 Dragan > thanks, > > greg k-h
