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Subject[PATCH v7 1/1] fpga: dfl: afu: harden port enable logic
Date
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.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Reviewed-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Acked-by: Wu Hao <hao.wu@intel.com>
---
v7:
- Added Acked-by tag from Wu Hao
v6:
- Fixed the dev_warn statement, which had "__func__" embedded in the
string instead of treated as a parameter to the format string.
v5:
- Added Reviewed-by tag to commit message
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..ab7be6217368 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, "%s: received 0x%llx, expected 0x%llx\n",
+ __func__, 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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