Messages in this thread | | | Date | Mon, 16 Jan 2023 16:07:16 +0530 | Subject | Re: [PATCH net-next v2] net: ethernet: ti: am65-cpsw/cpts: Fix CPTS release action | From | Siddharth Vadapalli <> |
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On 16/01/23 15:34, Leon Romanovsky wrote: > 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.
You are right! I apologize for not analyzing the cases well enough. The only case where common->cpts will remain NULL and the am65_cpsw_cpts_cleanup() function is invoked, is the case where the CONFIG_TI_K3_AM65_CPTS config is disabled. As you had pointed it out, in this case, the am65_cpts_release() is NOP, so passing the NULL pointer common->cpts will have no effect.
With this, I understand that the am65_cpsw_cpts_cleanup() function is unnecessary like you had mentioned, and am65_cpts_release() can be directly invoked for common->cpts. Please let me know if my understanding is correct. If so, I will implement this in the v3 patch.
Regards, Siddharth.
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