Messages in this thread | | | Subject | Re: [PATCH v2 1/1] fpga: dfl: afu: harden port enable logic | From | Russ Weight <> | Date | Tue, 2 Feb 2021 12:32:15 -0800 |
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On 9/17/20 1:28 PM, Tom Rix wrote: > On 9/17/20 11:32 AM, 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. >> >> Signed-off-by: Russ Weight <russell.h.weight@intel.com> >> --- >> drivers/fpga/dfl-afu-error.c | 2 +- >> drivers/fpga/dfl-afu-main.c | 29 +++++++++++++++++++++-------- >> drivers/fpga/dfl-afu.h | 2 +- >> 3 files changed, 23 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/fpga/dfl-afu-error.c b/drivers/fpga/dfl-afu-error.c >> index c4691187cca9..0806532a3e9f 100644 >> --- a/drivers/fpga/dfl-afu-error.c >> +++ b/drivers/fpga/dfl-afu-error.c >> @@ -103,7 +103,7 @@ static int afu_port_err_clear(struct device *dev, u64 err) >> __afu_port_err_mask(dev, false); >> > There is an earlier bit that sets ret = -EINVAL. > > This error will be lost or not handled well. > > Right now it doesn't seem to be handled. Good catch. I'll give priority to -EINVAL in the next version of the patch, as it is more informative in the context of this function. > >> /* Enable the Port by clear the reset */ >> - __afu_port_enable(pdev); >> + ret = __afu_port_enable(pdev); >> >> done: >> mutex_unlock(&pdata->lock); >> diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c >> index 753cda4b2568..f73b06cdf13c 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; > Is this really a success ? Maybe -EBUSY ? Yilun addressed this question in his previous response. This isessentially a reference count for nested disable calls. Weonly do the enable if the disable count has gone to zero, so this isn't an error condition. >> >> 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 >> @@ -111,7 +124,7 @@ static int __port_reset(struct platform_device *pdev) >> >> ret = __afu_port_disable(pdev); >> if (!ret) >> - __afu_port_enable(pdev); >> + ret = __afu_port_enable(pdev); >> >> return ret; >> } >> @@ -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); > The other functions in this file have afu_* since the __afu_port_enable/disable > > are used other places would it make sense to remove the '__' prefix ? > > If you think so, maybe a cleanup patch later. Yilun and Hao addressed this comment in their previous responses. We are using the '__' prefix to indicate highlight the fact caller needs to use care in managing the locking associated with these functions.
Thanks, - Russ > > Tom > >> >> void afu_mmio_region_init(struct dfl_feature_platform_data *pdata);
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