linux-kernel - Re: [PATCH] memory: dfl-emif: add the DFL EMIF private feature driver

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Date:   Fri, 11 Sep 2020 16:42:34 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     mdf@...nel.org, linux-kernel@...r.kernel.org, trix@...hat.com,
        matthew.gerlach@...ux.intel.com, russell.h.weight@...el.com,
        lgoncalv@...hat.com, hao.wu@...el.com, yilun.xu@...el.com
Subject: Re: [PATCH] memory: dfl-emif: add the DFL EMIF private feature driver

Sorry I missed one comments, see inline.

On Tue, Sep 08, 2020 at 12:01:02PM +0200, Krzysztof Kozlowski wrote:
> On Tue, Sep 08, 2020 at 04:27:25PM +0800, Xu Yilun wrote:
> > This driver is for the EMIF private feature implemented under FPGA
> > Device Feature List (DFL) framework. It is used to expose memory
> > interface status information as well as memory clearing control.
> > 
> > The purpose of memory clearing block is to zero out all private memory
> > when FPGA is to be reprogrammed. This gives users a reliable method to
> > prevent potential data leakage.
> > 
> > Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> > Signed-off-by: Russ Weight <russell.h.weight@...el.com>
> > ---
> >  .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
> >  drivers/memory/Kconfig                             |   9 +
> >  drivers/memory/Makefile                            |   2 +
> >  drivers/memory/dfl-emif.c                          | 211 +++++++++++++++++++++
> >  4 files changed, 247 insertions(+)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> >  create mode 100644 drivers/memory/dfl-emif.c
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif b/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> > new file mode 100644
> > index 0000000..33d557e
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> > @@ -0,0 +1,25 @@
> > +What:		/sys/bus/dfl/devices/dfl_dev.X/infX_cal_fail
> > +Date:		Sep 2020
> > +KernelVersion:	5.10
> > +Contact:	Xu Yilun <yilun.xu@...el.com>
> > +Description:	Read-only. It indicates if the calibration is failed on this
> > +		memory interface. "1" for calibration failure, "0" for OK.
> 
> "if the calibration failed"
> 
> > +		Format: %u
> > +
> > +What:		/sys/bus/dfl/devices/dfl_dev.X/infX_init_done
> > +Date:		Sep 2020
> > +KernelVersion:	5.10
> > +Contact:	Xu Yilun <yilun.xu@...el.com>
> > +Description:	Read-only. It indicates if the initialization is complete on
> > +		this memory interface. "1" for initialization complete, "0"
> > +		for not yet.
> > +		Format: %u
> 
> "if the initialization completed"
> 
> > +
> > +What:		/sys/bus/dfl/devices/dfl_dev.X/infX_clear
> > +Date:		Sep 2020
> > +KernelVersion:	5.10
> > +Contact:	Xu Yilun <yilun.xu@...el.com>
> > +Description:	Write-only. Writing "1" to this file will zero out all memory
> > +		data in this memory interface. Writing other values are
> > +		invalid.
> 
> "Writing of other values is invalid."
> 
> > +		Format: %u
> > diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
> > index 8072204..fb0858f 100644
> > --- a/drivers/memory/Kconfig
> > +++ b/drivers/memory/Kconfig
> > @@ -215,6 +215,15 @@ config STM32_FMC2_EBI
> >  	  devices (like SRAM, ethernet adapters, FPGAs, LCD displays, ...) on
> >  	  SOCs containing the FMC2 External Bus Interface.
> >  
> > +config FPGA_DFL_EMIF
> > +	tristate "DFL EMIF private feature support"
> > +	depends on FPGA_DFL && HAS_IOMEM
> 
> Cannot be compile tested without FPGA_DFL?

We need this FPGA_DFL dependency. The driver will use the
__dfl_driver_register(), which is defined in drivers/fpga/dfl.c, and
FPGA_DFL enables the compiling of dfl.c

Thanks,
Yilun