Hi Hans, On Fri, 6 Apr 2018 10:29:37 +0200 Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi, > > On 06-04-18 06:48, Kunihiko Hayashi wrote: > > Hi Hans, > > > On Thu, 5 Apr 2018 16:08:24 +0200 > > Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > >> Hi, > >> > >> On 05-04-18 16:00, Hans de Goede wrote: > >>> Hi, > >>>> On 05-04-18 15:54, Thierry Reding wrote: > >>>> On Thu, Apr 05, 2018 at 03:27:03PM +0200, Hans de Goede wrote: > >>>>> Hi, > >>>>> > >>>>> On 05-04-18 15:17, Patrice CHOTARD wrote: > >>>>>> Hi Thierry > >>>>>> > >>>>>> On 04/05/2018 11:54 AM, Thierry Reding wrote: > >>>>>>> On Fri, Mar 23, 2018 at 10:30:53AM +0900, Kunihiko Hayashi wrote: > >>>>>>>> Add support to get and control a list of resets for the device > >>>>>>>> as optional and shared. These resets must be kept de-asserted until > >>>>>>>> the device is enabled. > >>>>>>>> > >>>>>>>> This is specified as shared because some SoCs like UniPhier series > >>>>>>>> have common reset controls with all ahci controller instances. > >>>>>>>> > >>>>>>>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx> > >>>>>>>> --- > >>>>>>>> ??? .../devicetree/bindings/ata/ahci-platform.txt????? |? 1 + > >>>>>>>> ??? drivers/ata/ahci.h???????????????????????????????? |? 1 + > >>>>>>>> ??? drivers/ata/libahci_platform.c???????????????????? | 24 +++++++++++++++++++--- > >>>>>>>> ??? 3 files changed, 23 insertions(+), 3 deletions(-) > >>>>>>> > >>>>>>> This causes a regression on Tegra because we explicitly request the > >>>>>>> resets after the call to ahci_platform_get_resources(). > >>>>>> > >>>>>> I confirm, we got exactly the same behavior on STi platform. > >>>>>> > >>>>>>> > >>>>>>> ?? From a quick look, ahci_mtk and ahci_st are in the same boat, adding the > >>>>>>> corresponding maintainers to Cc. > >>>>>>> > >>>>>>> Patrice, Matthias: does SATA still work for you after this patch? This > >>>>>>> has been in linux-next since next-20180327. > >>>>>> > >>>>>> SATA is still working after this patch, but a kernel warning is > >>>>>> triggered due to the fact that resets are both requested by > >>>>>> libahci_platform and by ahci_st driver. > >>>>> > >>>>> So in your case you might be able to remove the reset handling > >>>>> from the ahci_st driver and rely on the new libahci_platform > >>>>> handling instead? If that works that seems like a win to me. > >>>>> > >>>>> As said elsewhere in this thread I think it makes sense to keep (or re-add > >>>>> after a revert) the libahci_platform reset code, but make it conditional > >>>>> on a flag passed to ahci_platform_get_resources(). This way we get > >>>>> the shared code for most cases and platforms which need special handling > >>>>> can opt-out. > >>>> > >>>> Agreed, although I prefer such helpers to be opt-in, rather than > >>>> opt-out. In my experience that tends make the helpers more resilient to > >>>> this kind of regression. It also simplifies things because instead of > >>>> drivers saying "I want all the helpers except this one and that one", > >>>> they can simply say "I want these helpers and that one". In the former > >>>> case whenever you add some new (opt-out) feature, you have to update all > >>>> drivers and add the exception. In the latter you only need to extend the > >>>> drivers that want to make use of the new helper. > >> > >> Erm, the idea never was to make this opt-out but rather opt in, so > >> we add a flags parameter to ahci_platform_get_resources() and all > >> current users pass in 0 for that to keep the current behavior. > >> > >> And only the generic drivers/ata/ahci_platform.c driver will pass > >> in a the new AHCI_PLATFORM_GET_RESETS flag, which makes > >> ahci_platform_get_resources() (and the other functions) also deal > >> with resets. > >> > >>>> With that in mind, rather than adding a flag to the > >>>> ahci_platform_get_resources() function, it might be more flexible to > >>>> split the helpers into finer-grained functions. That way drivers can > >>>> pick whatever functionality they want from the helpers. > >>>> Good point, so lets: > >>>> 1) Revert the patch for now > >>> 2) Have a new version of the patch which adds a ahci_platform_get_resets() helper > >>> 3) Modify the generic drivers/ata/ahci_platform.c driver to call the new > >>> ?? ahci_platform_get_resets() between its ahci_platform_get_resources() > >>> ?? and ahci_platform_enable_resources() calls. > >>> ?? I think that ahci_platform_enable_resources() should still automatically > >>> ?? do the right thing wrt resets if ahci_platform_get_resets() was called > >>> ?? (otherwise the resets array will be empty and should be skipped) > >>>> This should make the generic driver usable for the UniPhier SoCs and > >>> maybe some other drivers like the ahci_st driver can also switch to the > >>> new ahci_platform_get_resets() functionality to reduce their code a bit. > >> > >> So thinking slightly longer about this, with the opt-in variant > >> (which is what I intended all along) I do think that a flags parameter > >> is better, because the whole idea behind lib_ahci_platform is to avoid > >> having to do err = get_resource_a(), if (err) bail, err = get_resource_b() > >> if (err) bail, etc. in all the ahci (platform) drivers. And having fine > >> grained helpers re-introduces that. > > > In case of adding a flag instead of get_resource_a(), > > for example, we add the flag for use of resets, > > > -struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev) > > +struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev, > > + bool use_reset) > > > and for now all the drivers using this function need to add the argument as false > > to the caller. > > > - hpriv = ahci_platform_get_resources(pdev); > > + hpriv = ahci_platform_get_resources(pdev, false); > > > Surely this can avoid adding functions such get_resource_a(). If we apply another > > feature later, we add its flag as one of the arguments instead. Is it right? > > Yes, that is right, but instead of adding a "bool use_reset" please add > an "unsigned int flags" parameter instead and a: > > #define AHCI_PLATFORM_GET_RESETS 0x01 > > And update all callers of ahci_platform_get_resources to pass 0 for flags > except for drivers/ata/ahci_platform.c. This way we only need to modify > all callers once, and if we want to add another optional resource in > the future we can add a: > > #define AHCI_PLATFORM_GET_FOO 0x02 > > Without needing to change all callers again. Indeed. This is more flexible to add another resources. Although I'm about to prepare the candidate patch to fix this issue, I think we need to revert the previous patch first if some SoCs have issues because of it. Thank you, --- Best Regards, Kunihiko Hayashi -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
