Re: [PATCH v2 05/22] fpga: mgr: add status for fpga-mgr

[Wu Hao]

On Wed, Jul 12, 2017 at 10:22:17AM -0500, Alan Tull wrote:
> On Sun, Jun 25, 2017 at 8:52 PM, Wu Hao <hao.wu@xxxxxxxxx> wrote:
> 
> Hi Hao,
> 

Hi Alan

Thanks a lot for your feedback. : )

> > This patch adds status to fpga-manager data structure, to allow
> > driver to store full/partial reconfiguration errors and other
> > status information.
> >
> > one sysfs interface created for user space application to read
> > fpga-manager status.
> >
> > Signed-off-by: Wu Hao <hao.wu@xxxxxxxxx>
> > ---
> >  Documentation/ABI/testing/sysfs-class-fpga-manager | 10 +++++++++
> >  drivers/fpga/fpga-mgr.c                            | 24 ++++++++++++++++++++++
> >  include/linux/fpga/fpga-mgr.h                      |  9 ++++++++
> >  3 files changed, 43 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-class-fpga-manager b/Documentation/ABI/testing/sysfs-class-fpga-manager
> > index 23056c5..71b083e 100644
> > --- a/Documentation/ABI/testing/sysfs-class-fpga-manager
> > +++ b/Documentation/ABI/testing/sysfs-class-fpga-manager
> > @@ -35,3 +35,13 @@ Description: Read fpga manager state as a string.
> >                 * write complete        = Doing post programming steps
> >                 * write complete error  = Error while doing post programming
> >                 * operating             = FPGA is programmed and operating
> > +
> > +What:          /sys/class/fpga_manager/<fpga>/status
> > +Date:          June 2017
> > +KernelVersion: 4.12
> > +Contact:       Wu Hao <hao.wu@xxxxxxxxx>
> > +Description:   Read fpga manager status as a string.
> > +               If FPGA programming operation fails, it could be due to crc
> > +               error or incompatible bitstream image. The intent of this
> > +               interface is to provide more detailed information for FPGA
> > +               programming errors to userspace.
> > diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
> > index be13cce..2485658 100644
> > --- a/drivers/fpga/fpga-mgr.c
> > +++ b/drivers/fpga/fpga-mgr.c
> > @@ -388,12 +388,36 @@ static ssize_t state_show(struct device *dev,
> >         return sprintf(buf, "%s\n", state_str[mgr->state]);
> >  }
> >
> > +static ssize_t status_show(struct device *dev,
> > +                          struct device_attribute *attr, char *buf)
> > +{
> > +       struct fpga_manager *mgr = to_fpga_manager(dev);
> > +       int len = 0;
> > +
> > +       if (mgr->status & FPGA_MGR_STATUS_OPERATION_ERR)
> > +               len += sprintf(buf + len, "reconfig operation error\n");
> > +       if (mgr->status & FPGA_MGR_STATUS_CRC_ERR)
> > +               len += sprintf(buf + len, "reconfig crc error\n");
> > +       if (mgr->status & FPGA_MGR_STATUS_INCOMPATIBLE_BS_ERR)
> > +               len += sprintf(buf + len, "reconfig incompatible BS error\n");
> > +       if (mgr->status & FPGA_MGR_STATUS_IP_PROTOCOL_ERR)
> > +               len += sprintf(buf + len, "reconfig IP protocol error\n");
> > +       if (mgr->status & FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR)
> > +               len += sprintf(buf + len, "reconfig fifo overflow error\n");
> > +       if (mgr->status & FPGA_MGR_STATUS_SECURE_LOAD_ERR)
> > +               len += sprintf(buf + len, "reconfig secure load error\n");
> > +
> > +       return len;
> > +}
> > +
> >  static DEVICE_ATTR_RO(name);
> >  static DEVICE_ATTR_RO(state);
> > +static DEVICE_ATTR_RO(status);
> >
> >  static struct attribute *fpga_mgr_attrs[] = {
> >         &dev_attr_name.attr,
> >         &dev_attr_state.attr,
> > +       &dev_attr_status.attr,
> >         NULL,
> >  };
> >  ATTRIBUTE_GROUPS(fpga_mgr);
> > diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
> > index b222a57..8cb42ac 100644
> > --- a/include/linux/fpga/fpga-mgr.h
> > +++ b/include/linux/fpga/fpga-mgr.h
> > @@ -128,6 +128,14 @@ struct fpga_manager_ops {
> >         void (*fpga_remove)(struct fpga_manager *mgr);
> >  };
> >
> > +/* FPGA manager status: Partial/Full Reconfiguration errors */
> > +#define FPGA_MGR_STATUS_OPERATION_ERR          BIT(0)
> > +#define FPGA_MGR_STATUS_CRC_ERR                        BIT(1)
> > +#define FPGA_MGR_STATUS_INCOMPATIBLE_BS_ERR    BIT(2)
> 
> How about ..._INCOMPATIBLE_IMAGE_ERR? :)

Hm.. It sounds better to me. : )
Will change it in next version patch set.

> 
> > +#define FPGA_MGR_STATUS_IP_PROTOCOL_ERR                BIT(3)
> > +#define FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR      BIT(4)
> > +#define FPGA_MGR_STATUS_SECURE_LOAD_ERR                BIT(5)
> > +
> >  /**
> >   * struct fpga_manager - fpga manager structure
> >   * @name: name of low level fpga manager
> > @@ -142,6 +150,7 @@ struct fpga_manager {
> >         struct device dev;
> >         struct mutex ref_mutex;
> >         enum fpga_mgr_states state;
> > +       u64 status;
> 
> With this implementation, the low level driver sets ops->status and
> that could be stale by the time the framework looks at it.  I suggest
> adding a function to fpga_manager_ops that returns the status.  That
> way whenever the status is requested, the low level driver will have
> the opportunity to read status registers.
> 
> Besides this, this new sysfs looks helpful.

I get your point, then I will add one member to fpga_manager_ops.

@@ -118,6 +118,7 @@ struct fpga_image_info {
 struct fpga_manager_ops {
        size_t initial_header_size;
        enum fpga_mgr_states (*state)(struct fpga_manager *mgr);
+       u64 (*status)(struct fpga_manager *mgr);
        int (*write_init)(struct fpga_manager *mgr,
                          struct fpga_image_info *info,
                          const char *buf, size_t count);


and add common action to get status (pr error) in complete function.

@@ -139,6 +139,8 @@ static int fpga_mgr_write_complete(struct fpga_manager *mgr,
        if (ret) {
                dev_err(&mgr->dev, "Error after writing image data to FPGA\n");
                mgr->state = FPGA_MGR_STATE_WRITE_COMPLETE_ERR;
+               if (mgr->mops->status)
+                       mgr->status = mgr->mops->status(mgr);
                return ret;
        }
        mgr->state = FPGA_MGR_STATE_OPERATING;

after status is updated, then user could read it from the sysfs interface.

How do you think about this?

Thanks
Hao