Reviewed-by: Matthew Gerlach <matthew.gerl...@linux.intel.com>

On Thu, 4 Feb 2021, Russ Weight wrote:

Port enable is not complete until ACK = 0. Change
__afu_port_enable() to guarantee that the enable process
is complete by polling for ACK == 0.

Reviewed-by: Tom Rix <t...@redhat.com>
Signed-off-by: Russ Weight <russell.h.wei...@intel.com>
---
v4:
 - Added a dev_warn() call for the -EINVAL case of afu_port_err_clear()
 - Modified dev_err() message in __afu_port_disable() to say "disable"
   instead of "reset"
v3:
 - afu_port_err_clear() changed to prioritize port_enable failure over
   other a detected mismatch in port errors.
 - reorganized code in port_reset() to be more readable.
v2:
 - Fixed typo in commit message
---
drivers/fpga/dfl-afu-error.c | 10 ++++++----
drivers/fpga/dfl-afu-main.c  | 33 +++++++++++++++++++++++----------
drivers/fpga/dfl-afu.h       |  2 +-
3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/drivers/fpga/dfl-afu-error.c b/drivers/fpga/dfl-afu-error.c
index c4691187cca9..601e599fc33d 100644
--- a/drivers/fpga/dfl-afu-error.c
+++ b/drivers/fpga/dfl-afu-error.c
@@ -52,7 +52,7 @@ static int afu_port_err_clear(struct device *dev, u64 err)
        struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
        struct platform_device *pdev = to_platform_device(dev);
        void __iomem *base_err, *base_hdr;
-       int ret = -EBUSY;
+       int enable_ret = 0, ret = -EBUSY;
        u64 v;

        base_err = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_ERROR);
@@ -96,18 +96,20 @@ static int afu_port_err_clear(struct device *dev, u64 err)
                v = readq(base_err + PORT_FIRST_ERROR);
                writeq(v, base_err + PORT_FIRST_ERROR);
        } else {
+               dev_warn(dev, "__func__: received 0x%llx, expected 0x%llx\n",
+                        v, err);
                ret = -EINVAL;
        }

        /* Clear mask */
        __afu_port_err_mask(dev, false);

-       /* Enable the Port by clear the reset */
-       __afu_port_enable(pdev);
+       /* Enable the Port by clearing the reset */
+       enable_ret = __afu_port_enable(pdev);

done:
        mutex_unlock(&pdata->lock);
-       return ret;
+       return enable_ret ? enable_ret : ret;
}

static ssize_t errors_show(struct device *dev, struct device_attribute *attr,
diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index 753cda4b2568..77dadaae5b8f 100644
--- a/drivers/fpga/dfl-afu-main.c
+++ b/drivers/fpga/dfl-afu-main.c
@@ -21,6 +21,9 @@

#include "dfl-afu.h"

+#define RST_POLL_INVL 10 /* us */
+#define RST_POLL_TIMEOUT 1000 /* us */
+
/**
 * __afu_port_enable - enable a port by clear reset
 * @pdev: port platform device.
@@ -32,7 +35,7 @@
 *
 * The caller needs to hold lock for protection.
 */
-void __afu_port_enable(struct platform_device *pdev)
+int __afu_port_enable(struct platform_device *pdev)
{
        struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
        void __iomem *base;
@@ -41,7 +44,7 @@ void __afu_port_enable(struct platform_device *pdev)
        WARN_ON(!pdata->disable_count);

        if (--pdata->disable_count != 0)
-               return;
+               return 0;

        base = dfl_get_feature_ioaddr_by_id(&pdev->dev, PORT_FEATURE_ID_HEADER);

@@ -49,10 +52,20 @@ void __afu_port_enable(struct platform_device *pdev)
        v = readq(base + PORT_HDR_CTRL);
        v &= ~PORT_CTRL_SFTRST;
        writeq(v, base + PORT_HDR_CTRL);
-}

-#define RST_POLL_INVL 10 /* us */
-#define RST_POLL_TIMEOUT 1000 /* us */
+       /*
+        * HW clears the ack bit to indicate that the port is fully out
+        * of reset.
+        */
+       if (readq_poll_timeout(base + PORT_HDR_CTRL, v,
+                              !(v & PORT_CTRL_SFTRST_ACK),
+                              RST_POLL_INVL, RST_POLL_TIMEOUT)) {
+               dev_err(&pdev->dev, "timeout, failure to enable device\n");
+               return -ETIMEDOUT;
+       }
+
+       return 0;
+}

/**
 * __afu_port_disable - disable a port by hold reset
@@ -86,7 +99,7 @@ int __afu_port_disable(struct platform_device *pdev)
        if (readq_poll_timeout(base + PORT_HDR_CTRL, v,
                               v & PORT_CTRL_SFTRST_ACK,
                               RST_POLL_INVL, RST_POLL_TIMEOUT)) {
-               dev_err(&pdev->dev, "timeout, fail to reset device\n");
+               dev_err(&pdev->dev, "timeout, failure to disable device\n");
                return -ETIMEDOUT;
        }

@@ -111,9 +124,9 @@ static int __port_reset(struct platform_device *pdev)

        ret = __afu_port_disable(pdev);
        if (!ret)
-               __afu_port_enable(pdev);
+               return ret;

-       return ret;
+       return __afu_port_enable(pdev);
}

static int port_reset(struct platform_device *pdev)
@@ -872,11 +885,11 @@ static int afu_dev_destroy(struct platform_device *pdev)
static int port_enable_set(struct platform_device *pdev, bool enable)
{
        struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
-       int ret = 0;
+       int ret;

        mutex_lock(&pdata->lock);
        if (enable)
-               __afu_port_enable(pdev);
+               ret = __afu_port_enable(pdev);
        else
                ret = __afu_port_disable(pdev);
        mutex_unlock(&pdata->lock);
diff --git a/drivers/fpga/dfl-afu.h b/drivers/fpga/dfl-afu.h
index 576e94960086..e5020e2b1f3d 100644
--- a/drivers/fpga/dfl-afu.h
+++ b/drivers/fpga/dfl-afu.h
@@ -80,7 +80,7 @@ struct dfl_afu {
};

/* hold pdata->lock when call __afu_port_enable/disable */
-void __afu_port_enable(struct platform_device *pdev);
+int __afu_port_enable(struct platform_device *pdev);
int __afu_port_disable(struct platform_device *pdev);

void afu_mmio_region_init(struct dfl_feature_platform_data *pdata);
--
2.25.1


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