From: Leon Romanovsky <leon@kernel.org>
To: Siddharth Vadapalli <s-vadapalli@ti.com>
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
linux@armlinux.org.uk, pabeni@redhat.com, rogerq@kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, vigneshr@ti.com,
srk@ti.com
Subject: Re: [PATCH net-next v2] net: ethernet: ti: am65-cpsw/cpts: Fix CPTS release action
Date: Mon, 16 Jan 2023 12:04:33 +0200 [thread overview]
Message-ID: <Y8UhMVPTo3qVgkyc@unreal> (raw)
In-Reply-To: <f83831f8-b827-18df-36d4-48d9ff0056e1@ti.com>
On Mon, Jan 16, 2023 at 01:13:36PM +0530, Siddharth Vadapalli wrote:
>
>
> On 16/01/23 13:00, Leon Romanovsky wrote:
> > On Mon, Jan 16, 2023 at 10:15:17AM +0530, Siddharth Vadapalli wrote:
> >> The am65_cpts_release() function is registered as a devm_action in the
> >> am65_cpts_create() function in am65-cpts driver. When the am65-cpsw driver
> >> invokes am65_cpts_create(), am65_cpts_release() is added in the set of devm
> >> actions associated with the am65-cpsw driver's device.
> >>
> >> In the event of probe failure or probe deferral, the platform_drv_probe()
> >> function invokes dev_pm_domain_detach() which powers off the CPSW and the
> >> CPSW's CPTS hardware, both of which share the same power domain. Since the
> >> am65_cpts_disable() function invoked by the am65_cpts_release() function
> >> attempts to reset the CPTS hardware by writing to its registers, the CPTS
> >> hardware is assumed to be powered on at this point. However, the hardware
> >> is powered off before the devm actions are executed.
> >>
> >> Fix this by getting rid of the devm action for am65_cpts_release() and
> >> invoking it directly on the cleanup and exit paths.
> >>
> >> Fixes: f6bd59526ca5 ("net: ethernet: ti: introduce am654 common platform time sync driver")
> >> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> >> Reviewed-by: Roger Quadros <rogerq@kernel.org>
> >> ---
> >> Changes from v1:
> >> 1. Fix the build issue when "CONFIG_TI_K3_AM65_CPTS" is not set. This
> >> error was reported by kernel test robot <lkp@intel.com> at:
> >> https://lore.kernel.org/r/202301142105.lt733Lt3-lkp@intel.com/
> >> 2. Collect Reviewed-by tag from Roger Quadros.
> >>
> >> v1:
> >> https://lore.kernel.org/r/20230113104816.132815-1-s-vadapalli@ti.com/
> >>
> >> drivers/net/ethernet/ti/am65-cpsw-nuss.c | 8 ++++++++
> >> drivers/net/ethernet/ti/am65-cpts.c | 15 +++++----------
> >> drivers/net/ethernet/ti/am65-cpts.h | 5 +++++
> >> 3 files changed, 18 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> >> index 5cac98284184..00f25d8a026b 100644
> >> --- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> >> +++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> >> @@ -1913,6 +1913,12 @@ static int am65_cpsw_am654_get_efuse_macid(struct device_node *of_node,
> >> return 0;
> >> }
> >>
> >> +static void am65_cpsw_cpts_cleanup(struct am65_cpsw_common *common)
> >> +{
> >> + if (IS_ENABLED(CONFIG_TI_K3_AM65_CPTS) && common->cpts)
> >
> > Why do you have IS_ENABLED(CONFIG_TI_K3_AM65_CPTS), if
> > am65_cpts_release() defined as empty when CONFIG_TI_K3_AM65_CPTS not set?
> >
> > How is it possible to have common->cpts == NULL?
>
> Thank you for reviewing the patch. I realize now that checking
> CONFIG_TI_K3_AM65_CPTS is unnecessary.
>
> common->cpts remains NULL in the following cases:
> 1. am65_cpsw_init_cpts() returns 0 since CONFIG_TI_K3_AM65_CPTS is not enabled.
In this case am65_cpsw_cpts_cleanup() will NOP as well.
> 2. am65_cpsw_init_cpts() returns -ENOENT since the cpts node is not defined.
It is an error and all callers unwind properly.
> 3. The call to am65_cpts_create() fails within the am65_cpsw_init_cpts()
> function with a return value of 0 when cpts is disabled.
It is disabled by CONFIG_TI_K3_AM65_CPTS, which in turn will make
am65_cpsw_cpts_cleanup() NOP.
> 4. The call to am65_cpts_create() within the am65_cpsw_init_cpts() function
> fails with an error.
>
> Of the above cases, the am65_cpsw_cpts_cleanup() function would have to handle
> cases 1 and 3, since the probe might fail at a later point, following which the
> probe cleanup path will invoke the am65_cpts_cpts_cleanup() function. This
> function then checks for common->cpts not being NULL, so that it can invoke the
> am65_cpts_release() function with this pointer.
I still don't see how it is possible.
Thanks
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next prev parent reply other threads:[~2023-01-16 10:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-16 4:45 [PATCH net-next v2] net: ethernet: ti: am65-cpsw/cpts: Fix CPTS release action Siddharth Vadapalli
2023-01-16 7:30 ` Leon Romanovsky
2023-01-16 7:43 ` Siddharth Vadapalli
2023-01-16 10:04 ` Leon Romanovsky [this message]
2023-01-16 10:37 ` Siddharth Vadapalli
2023-01-16 11:26 ` Leon Romanovsky
2023-01-16 16:01 ` Roger Quadros
2023-01-17 5:00 ` Siddharth Vadapalli
2023-01-17 9:27 ` Roger Quadros
2023-01-17 9:48 ` Siddharth Vadapalli
2023-01-17 11:34 ` Leon Romanovsky
2023-01-18 4:58 ` Siddharth Vadapalli
2023-01-18 7:25 ` Roger Quadros
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