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Date: Wed, 10 Apr 2019 09:43:58 +0800
From: Wu Hao <hao.wu@...el.com>
To: Alan Tull <atull@...nel.org>
Cc: Moritz Fischer <mdf@...nel.org>, linux-fpga@...r.kernel.org,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-api@...r.kernel.org, Xu Yilun <yilun.xu@...el.com>
Subject: Re: [PATCH 11/17] fpga: dfl: afu: add error reporting support.
On Tue, Apr 09, 2019 at 03:57:37PM -0500, Alan Tull wrote:
> On Sun, Mar 24, 2019 at 10:24 PM Wu Hao <hao.wu@...el.com> wrote:
>
> Hi Hao,
>
> >
> > Error reporting is one important private feature, it reports error
> > detected on port and accelerated function unit (AFU). It introduces
> > several sysfs interfaces to allow userspace to check and clear
> > errors detected by hardware.
> >
> > Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> > Signed-off-by: Wu Hao <hao.wu@...el.com>
> > ---
> > Documentation/ABI/testing/sysfs-platform-dfl-port | 29 +++
> > drivers/fpga/Makefile | 1 +
> > drivers/fpga/dfl-afu-error.c | 225 ++++++++++++++++++++++
> > drivers/fpga/dfl-afu-main.c | 4 +
> > drivers/fpga/dfl-afu.h | 4 +
> > 5 files changed, 263 insertions(+)
> > create mode 100644 drivers/fpga/dfl-afu-error.c
> >
> > diff --git a/Documentation/ABI/testing/sysfs-platform-dfl-port b/Documentation/ABI/testing/sysfs-platform-dfl-port
> > index f611e47..e6140aa 100644
> > --- a/Documentation/ABI/testing/sysfs-platform-dfl-port
> > +++ b/Documentation/ABI/testing/sysfs-platform-dfl-port
> > @@ -79,3 +79,32 @@ KernelVersion: 5.2
> > Contact: Wu Hao <hao.wu@...el.com>
> > Description: Read-only. Read this file to get the status of issued command
> > to userclck_freqcntrcmd.
> > +
> > +What: /sys/bus/platform/devices/dfl-port.0/errors/errors
> > +Date: March 2019
> > +KernelVersion: 5.2
> > +Contact: Wu Hao <hao.wu@...el.com>
> > +Description: Read-only. Read this file to get errors detected on port and
> > + Accelerated Function Unit (AFU).
> > +
> > +What: /sys/bus/platform/devices/dfl-port.0/errors/first_error
> > +Date: March 2019
> > +KernelVersion: 5.2
> > +Contact: Wu Hao <hao.wu@...el.com>
> > +Description: Read-only. Read this file to get the first error detected by
> > + hardware.
> > +
> > +What: /sys/bus/platform/devices/dfl-port.0/errors/first_malformed_req
> > +Date: March 2019
> > +KernelVersion: 5.2
> > +Contact: Wu Hao <hao.wu@...el.com>
> > +Description: Read-only. Read this file to get the first malformed request
> > + captured by hardware.
> > +
> > +What: /sys/bus/platform/devices/dfl-port.0/errors/clear
> > +Date: March 2019
> > +KernelVersion: 5.2
> > +Contact: Wu Hao <hao.wu@...el.com>
> > +Description: Write-only. Write error code to this file to clear errors. If
> > + the input error code doesn't match, it returns -EBUSY error
> > + code.
>
> I understand how -EBUSY could be the right error code for when the
> hardware is in a state where the error can't be cleared. But if the
> input error code doesn't match, shouldn't the code be -EINVAL? Also
> as noted below, the way this is currently coded, -ETIMEDOUT could get
> returned.
Thanks for the comments, let me try to capture all possible error return
values in doc in the next version to avoid confusion.
>
> > diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> > index c0dd4c8..f1f0af7 100644
> > --- a/drivers/fpga/Makefile
> > +++ b/drivers/fpga/Makefile
> > @@ -40,6 +40,7 @@ obj-$(CONFIG_FPGA_DFL_AFU) += dfl-afu.o
> >
> > dfl-fme-objs := dfl-fme-main.o dfl-fme-pr.o
> > dfl-afu-objs := dfl-afu-main.o dfl-afu-region.o dfl-afu-dma-region.o
> > +dfl-afu-objs += dfl-afu-error.o
> >
> > # Drivers for FPGAs which implement DFL
> > obj-$(CONFIG_FPGA_DFL_PCI) += dfl-pci.o
> > diff --git a/drivers/fpga/dfl-afu-error.c b/drivers/fpga/dfl-afu-error.c
> > new file mode 100644
> > index 0000000..b66bd4a
> > --- /dev/null
> > +++ b/drivers/fpga/dfl-afu-error.c
> > @@ -0,0 +1,225 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Driver for FPGA Accelerated Function Unit (AFU) Error Reporting
> > + *
> > + * Copyright 2019 Intel Corporation, Inc.
> > + *
> > + * Authors:
> > + * Wu Hao <hao.wu@...ux.intel.com>
> > + * Xiao Guangrong <guangrong.xiao@...ux.intel.com>
> > + * Joseph Grecco <joe.grecco@...el.com>
> > + * Enno Luebbers <enno.luebbers@...el.com>
> > + * Tim Whisonant <tim.whisonant@...el.com>
> > + * Ananda Ravuri <ananda.ravuri@...el.com>
> > + * Mitchel Henry <henry.mitchel@...el.com>
> > + */
> > +
> > +#include <linux/uaccess.h>
> > +
> > +#include "dfl-afu.h"
> > +
> > +#define PORT_ERROR_MASK 0x8
> > +#define PORT_ERROR 0x10
> > +#define PORT_FIRST_ERROR 0x18
> > +#define PORT_MALFORMED_REQ0 0x20
> > +#define PORT_MALFORMED_REQ1 0x28
> > +
> > +#define ERROR_MASK GENMASK_ULL(63, 0)
> > +
> > +/* mask or unmask port errors by the error mask register. */
> > +static void __port_err_mask(struct device *dev, bool mask)
> > +{
> > + void __iomem *base;
> > +
> > + base = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_ERROR);
> > +
> > + writeq(mask ? ERROR_MASK : 0, base + PORT_ERROR_MASK);
> > +}
> > +
> > +/* clear port errors. */
> > +static int __port_err_clear(struct device *dev, u64 err)
> > +{
> > + struct platform_device *pdev = to_platform_device(dev);
> > + void __iomem *base_err, *base_hdr;
> > + int ret;
> > + u64 v;
> > +
> > + base_err = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_ERROR);
> > + base_hdr = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_HEADER);
> > +
> > + /*
> > + * clear Port Errors
> > + *
> > + * - Check for AP6 State
> > + * - Halt Port by keeping Port in reset
> > + * - Set PORT Error mask to all 1 to mask errors
> > + * - Clear all errors
> > + * - Set Port mask to all 0 to enable errors
> > + * - All errors start capturing new errors
> > + * - Enable Port by pulling the port out of reset
> > + */
> > +
> > + /* if device is still in AP6 power state, can not clear any error. */
> > + v = readq(base_hdr + PORT_HDR_STS);
> > + if (FIELD_GET(PORT_STS_PWR_STATE, v) == PORT_STS_PWR_STATE_AP6) {
> > + dev_err(dev, "Could not clear errors, device in AP6 state.\n");
> > + return -EBUSY;
> > + }
> > +
> > + /* Halt Port by keeping Port in reset */
> > + ret = __port_disable(pdev);
> > + if (ret)
> > + return ret;
>
> __port_disable can return -ETIMEDOUT which will then get returned from
> clear_store. The sysfs document only talks about -EBUSY. You could
> either document -ETIMEDOUT in the sysfs doc or you could change the
> code to adjust the returned error code.
Yes, agree.
>
> > +
> > + /* Mask all errors */
> > + __port_err_mask(dev, true);
> > +
> > + /* Clear errors if err input matches with current port errors.*/
> > + v = readq(base_err + PORT_ERROR);
> > +
> > + if (v == err) {
> > + writeq(v, base_err + PORT_ERROR);
> > +
> > + v = readq(base_err + PORT_FIRST_ERROR);
> > + writeq(v, base_err + PORT_FIRST_ERROR);
> > + } else {
> > + ret = -EBUSY;
> > + }
> > +
> > + /* Clear mask */
> > + __port_err_mask(dev, false);
> > +
> > + /* Enable the Port by clear the reset */
> > + __port_enable(pdev);
> > +
> > + return ret;
> > +}
> > +
> > +static ssize_t revision_show(struct device *dev, struct device_attribute *attr,
> > + char *buf)
> > +{
> > + void __iomem *base;
> > +
> > + base = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_ERROR);
> > +
> > + return scnprintf(buf, PAGE_SIZE, "%u\n", dfl_feature_revision(base));
> > +}
> > +static DEVICE_ATTR_RO(revision);
>
> This appears to be adding a
> /sys/bus/platform/devices/dfl-port.0/errors/revision attribute that
> isn't documented in the sysfs document.
Sorry, will fix all above issues in the next version.
Thanks again for the code review and comments.
Hao
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