| Message ID | fdaf2e41bb6a0c5118ff9cc21f4f62583208d885.1718655070.git.dsimic@manjaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/lima: Mark simple_ondemand governor as softdep | expand |
I see the problem that initramfs need to build a module dependency chain, but lima does not call any symbol from simpleondemand governor module. softdep module seems to be optional while our dependency is hard one, can we just add MODULE_INFO(depends, _depends), or create a new macro called MODULE_DEPENDS()? On Tue, Jun 18, 2024 at 4:22 AM Dragan Simic <dsimic@manjaro.org> wrote: > > Lima DRM driver uses devfreq to perform DVFS, while using simple_ondemand > devfreq governor by default. This causes driver initialization to fail on > boot when simple_ondemand governor isn't built into the kernel statically, > as a result of the missing module dependency and, consequently, the required > governor module not being included in the initial ramdisk. Thus, let's mark > simple_ondemand governor as a softdep for Lima, to have its kernel module > included in the initial ramdisk. > > This is a rather longstanding issue that has forced distributions to build > devfreq governors statically into their kernels, [1][2] or may have forced > some users to introduce unnecessary workarounds. > > Having simple_ondemand marked as a softdep for Lima may not resolve this > issue for all Linux distributions. In particular, it will remain unresolved > for the distributions whose utilities for the initial ramdisk generation do > not handle the available softdep information [3] properly yet. However, some > Linux distributions already handle softdeps properly while generating their > initial ramdisks, [4] and this is a prerequisite step in the right direction > for the distributions that don't handle them properly yet. > > [1] https://gitlab.manjaro.org/manjaro-arm/packages/core/linux-pinephone/-/blob/6.7-megi/config?ref_type=heads#L5749 > [2] https://gitlab.com/postmarketOS/pmaports/-/blob/7f64e287e7732c9eaa029653e73ca3d4ba1c8598/main/linux-postmarketos-allwinner/config-postmarketos-allwinner.aarch64#L4654 > [3] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d > [4] https://github.com/archlinux/mkinitcpio/commit/97ac4d37aae084a050be512f6d8f4489054668ad > > Cc: Philip Muller <philm@manjaro.org> > Cc: Oliver Smith <ollieparanoid@postmarketos.org> > Cc: Daniel Smith <danct12@disroot.org> > Cc: stable@vger.kernel.org > Fixes: 1996970773a3 ("drm/lima: Add optional devfreq and cooling device support") > Signed-off-by: Dragan Simic <dsimic@manjaro.org> > --- > drivers/gpu/drm/lima/lima_drv.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/lima/lima_drv.c b/drivers/gpu/drm/lima/lima_drv.c > index 739c865b556f..10bce18b7c31 100644 > --- a/drivers/gpu/drm/lima/lima_drv.c > +++ b/drivers/gpu/drm/lima/lima_drv.c > @@ -501,3 +501,4 @@ module_platform_driver(lima_platform_driver); > MODULE_AUTHOR("Lima Project Developers"); > MODULE_DESCRIPTION("Lima DRM Driver"); > MODULE_LICENSE("GPL v2"); > +MODULE_SOFTDEP("pre: governor_simpleondemand");
On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: > > I see the problem that initramfs need to build a module dependency chain, > but lima does not call any symbol from simpleondemand governor module. > > softdep module seems to be optional while our dependency is hard one, > can we just add MODULE_INFO(depends, _depends), or create a new > macro called MODULE_DEPENDS()? > This doesn't work on my side because depmod generates modules.dep by symbol lookup instead of modinfo section. So softdep may be our only choice to add module dependency manually. I can accept the softdep first, then make PM optional later. > On Tue, Jun 18, 2024 at 4:22 AM Dragan Simic <dsimic@manjaro.org> wrote: > > > > Lima DRM driver uses devfreq to perform DVFS, while using simple_ondemand > > devfreq governor by default. This causes driver initialization to fail on > > boot when simple_ondemand governor isn't built into the kernel statically, > > as a result of the missing module dependency and, consequently, the required > > governor module not being included in the initial ramdisk. Thus, let's mark > > simple_ondemand governor as a softdep for Lima, to have its kernel module > > included in the initial ramdisk. > > > > This is a rather longstanding issue that has forced distributions to build > > devfreq governors statically into their kernels, [1][2] or may have forced > > some users to introduce unnecessary workarounds. > > > > Having simple_ondemand marked as a softdep for Lima may not resolve this > > issue for all Linux distributions. In particular, it will remain unresolved > > for the distributions whose utilities for the initial ramdisk generation do > > not handle the available softdep information [3] properly yet. However, some > > Linux distributions already handle softdeps properly while generating their > > initial ramdisks, [4] and this is a prerequisite step in the right direction > > for the distributions that don't handle them properly yet. > > > > [1] https://gitlab.manjaro.org/manjaro-arm/packages/core/linux-pinephone/-/blob/6.7-megi/config?ref_type=heads#L5749 > > [2] https://gitlab.com/postmarketOS/pmaports/-/blob/7f64e287e7732c9eaa029653e73ca3d4ba1c8598/main/linux-postmarketos-allwinner/config-postmarketos-allwinner.aarch64#L4654 > > [3] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d > > [4] https://github.com/archlinux/mkinitcpio/commit/97ac4d37aae084a050be512f6d8f4489054668ad > > > > Cc: Philip Muller <philm@manjaro.org> > > Cc: Oliver Smith <ollieparanoid@postmarketos.org> > > Cc: Daniel Smith <danct12@disroot.org> > > Cc: stable@vger.kernel.org > > Fixes: 1996970773a3 ("drm/lima: Add optional devfreq and cooling device support") > > Signed-off-by: Dragan Simic <dsimic@manjaro.org> > > --- > > drivers/gpu/drm/lima/lima_drv.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/gpu/drm/lima/lima_drv.c b/drivers/gpu/drm/lima/lima_drv.c > > index 739c865b556f..10bce18b7c31 100644 > > --- a/drivers/gpu/drm/lima/lima_drv.c > > +++ b/drivers/gpu/drm/lima/lima_drv.c > > @@ -501,3 +501,4 @@ module_platform_driver(lima_platform_driver); > > MODULE_AUTHOR("Lima Project Developers"); > > MODULE_DESCRIPTION("Lima DRM Driver"); > > MODULE_LICENSE("GPL v2"); > > +MODULE_SOFTDEP("pre: governor_simpleondemand");
On Tue, Jun 18, 2024 at 04:01:26PM GMT, Qiang Yu wrote: > On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: > > > > I see the problem that initramfs need to build a module dependency chain, > > but lima does not call any symbol from simpleondemand governor module. > > > > softdep module seems to be optional while our dependency is hard one, > > can we just add MODULE_INFO(depends, _depends), or create a new > > macro called MODULE_DEPENDS()? > > > This doesn't work on my side because depmod generates modules.dep > by symbol lookup instead of modinfo section. So softdep may be our only > choice to add module dependency manually. I can accept the softdep > first, then make PM optional later. It's still super fragile, and depends on the user not changing the policy. It should be solved in some other, more robust way. Maxime
Hello Qiang and Maxime, On 2024-06-18 10:13, Maxime Ripard wrote: > On Tue, Jun 18, 2024 at 04:01:26PM GMT, Qiang Yu wrote: >> On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: >> > >> > I see the problem that initramfs need to build a module dependency chain, >> > but lima does not call any symbol from simpleondemand governor module. >> > softdep module seems to be optional while our dependency is hard one, >> > can we just add MODULE_INFO(depends, _depends), or create a new >> > macro called MODULE_DEPENDS()? I had the same thoughts, because softdeps are for optional module dependencies, while in this case it's a hard dependency. Though, I went with adding a softdep, simply because I saw no better option available. >> This doesn't work on my side because depmod generates modules.dep >> by symbol lookup instead of modinfo section. So softdep may be our >> only >> choice to add module dependency manually. I can accept the softdep >> first, then make PM optional later. I also thought about making devfreq optional in the Lima driver, which would make this additional softdep much more appropriate. Though, I'm not really sure that's a good approach, because not having working devfreq for Lima might actually cause issues on some devices, such as increased power consumption. In other words, it might be better to have Lima probing fail if devfreq can't be initialized, rather than having probing succeed with no working devfreq. Basically, failed probing is obvious, while a warning in the kernel log about no devfreq might easily be overlooked, causing regressions on some devices. > It's still super fragile, and depends on the user not changing the > policy. It should be solved in some other, more robust way. I see, but I'm not really sure how to make it more robust? In the end, some user can blacklist the simple_ondemand governor module, and we can't do much about it. Introducing harddeps alongside softdeps would make sense from the design standpoint, but the amount of required changes wouldn't be trivial at all, on various levels.
On 2024-06-18 12:33, Dragan Simic wrote: > Hello Qiang and Maxime, > > On 2024-06-18 10:13, Maxime Ripard wrote: >> On Tue, Jun 18, 2024 at 04:01:26PM GMT, Qiang Yu wrote: >>> On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: >>> > >>> > I see the problem that initramfs need to build a module dependency chain, >>> > but lima does not call any symbol from simpleondemand governor module. >>> > softdep module seems to be optional while our dependency is hard one, >>> > can we just add MODULE_INFO(depends, _depends), or create a new >>> > macro called MODULE_DEPENDS()? > > I had the same thoughts, because softdeps are for optional module > dependencies, while in this case it's a hard dependency. Though, > I went with adding a softdep, simply because I saw no better option > available. > >>> This doesn't work on my side because depmod generates modules.dep >>> by symbol lookup instead of modinfo section. So softdep may be our >>> only >>> choice to add module dependency manually. I can accept the softdep >>> first, then make PM optional later. > > I also thought about making devfreq optional in the Lima driver, > which would make this additional softdep much more appropriate. > Though, I'm not really sure that's a good approach, because not > having working devfreq for Lima might actually cause issues on > some devices, such as increased power consumption. > > In other words, it might be better to have Lima probing fail if > devfreq can't be initialized, rather than having probing succeed > with no working devfreq. Basically, failed probing is obvious, > while a warning in the kernel log about no devfreq might easily > be overlooked, causing regressions on some devices. > >> It's still super fragile, and depends on the user not changing the >> policy. It should be solved in some other, more robust way. > > I see, but I'm not really sure how to make it more robust? In > the end, some user can blacklist the simple_ondemand governor > module, and we can't do much about it. > > Introducing harddeps alongside softdeps would make sense from > the design standpoint, but the amount of required changes wouldn't > be trivial at all, on various levels. After further investigation, it seems that the softdeps have already seen a fair amount of abuse for what they actually aren't intended, i.e. resolving hard dependencies. For example, have a look at the commit d5178578bcd4 (btrfs: directly call into crypto framework for checksumming) [1] and the lines containing MODULE_SOFTDEP() at the very end of fs/btrfs/super.c. [2] If a filesystem driver can rely on the abuse of softdeps, which admittedly are a bit fragile, I think we can follow the same approach, at least for now. With all that in mind, I think that accepting this patch, as well as the related Panfrost patch, [3] should be warranted. I'd keep investigating the possibility of introducing harddeps in form of MODULE_HARDDEP() and the related support in kmod project, similar to the already existing softdep support, [4] but that will inevitably take a lot of time, both for implementing it and for reaching various Linux distributions, which is another reason why accepting these patches seems reasonable. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5178578bcd4 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/super.c#n2593 [3] https://lore.kernel.org/dri-devel/4e1e00422a14db4e2a80870afb704405da16fd1b.1718655077.git.dsimic@manjaro.org/ [4] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d
Hello everyone, Just checking, any further thoughts about this patch? On 2024-06-18 21:22, Dragan Simic wrote: > On 2024-06-18 12:33, Dragan Simic wrote: >> On 2024-06-18 10:13, Maxime Ripard wrote: >>> On Tue, Jun 18, 2024 at 04:01:26PM GMT, Qiang Yu wrote: >>>> On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: >>>> > >>>> > I see the problem that initramfs need to build a module dependency chain, >>>> > but lima does not call any symbol from simpleondemand governor module. >>>> > softdep module seems to be optional while our dependency is hard one, >>>> > can we just add MODULE_INFO(depends, _depends), or create a new >>>> > macro called MODULE_DEPENDS()? >> >> I had the same thoughts, because softdeps are for optional module >> dependencies, while in this case it's a hard dependency. Though, >> I went with adding a softdep, simply because I saw no better option >> available. >> >>>> This doesn't work on my side because depmod generates modules.dep >>>> by symbol lookup instead of modinfo section. So softdep may be our >>>> only >>>> choice to add module dependency manually. I can accept the softdep >>>> first, then make PM optional later. >> >> I also thought about making devfreq optional in the Lima driver, >> which would make this additional softdep much more appropriate. >> Though, I'm not really sure that's a good approach, because not >> having working devfreq for Lima might actually cause issues on >> some devices, such as increased power consumption. >> >> In other words, it might be better to have Lima probing fail if >> devfreq can't be initialized, rather than having probing succeed >> with no working devfreq. Basically, failed probing is obvious, >> while a warning in the kernel log about no devfreq might easily >> be overlooked, causing regressions on some devices. >> >>> It's still super fragile, and depends on the user not changing the >>> policy. It should be solved in some other, more robust way. >> >> I see, but I'm not really sure how to make it more robust? In >> the end, some user can blacklist the simple_ondemand governor >> module, and we can't do much about it. >> >> Introducing harddeps alongside softdeps would make sense from >> the design standpoint, but the amount of required changes wouldn't >> be trivial at all, on various levels. > > After further investigation, it seems that the softdeps have > already seen a fair amount of abuse for what they actually aren't > intended, i.e. resolving hard dependencies. For example, have > a look at the commit d5178578bcd4 (btrfs: directly call into > crypto framework for checksumming) [1] and the lines containing > MODULE_SOFTDEP() at the very end of fs/btrfs/super.c. [2] > > If a filesystem driver can rely on the abuse of softdeps, which > admittedly are a bit fragile, I think we can follow the same > approach, at least for now. > > With all that in mind, I think that accepting this patch, as well > as the related Panfrost patch, [3] should be warranted. I'd keep > investigating the possibility of introducing harddeps in form > of MODULE_HARDDEP() and the related support in kmod project, > similar to the already existing softdep support, [4] but that > will inevitably take a lot of time, both for implementing it > and for reaching various Linux distributions, which is another > reason why accepting these patches seems reasonable. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5178578bcd4 > [2] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/super.c#n2593 > [3] > https://lore.kernel.org/dri-devel/4e1e00422a14db4e2a80870afb704405da16fd1b.1718655077.git.dsimic@manjaro.org/ > [4] > https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d
On Wed, Jun 26, 2024 at 2:15 AM Dragan Simic <dsimic@manjaro.org> wrote: > > Hello everyone, > > Just checking, any further thoughts about this patch? > I'm OK with this as a temp workaround because it's simple and do no harm even it's not perfect. If no other better suggestion for short term, I'll submit this at weekend. > On 2024-06-18 21:22, Dragan Simic wrote: > > On 2024-06-18 12:33, Dragan Simic wrote: > >> On 2024-06-18 10:13, Maxime Ripard wrote: > >>> On Tue, Jun 18, 2024 at 04:01:26PM GMT, Qiang Yu wrote: > >>>> On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: > >>>> > > >>>> > I see the problem that initramfs need to build a module dependency chain, > >>>> > but lima does not call any symbol from simpleondemand governor module. > >>>> > softdep module seems to be optional while our dependency is hard one, > >>>> > can we just add MODULE_INFO(depends, _depends), or create a new > >>>> > macro called MODULE_DEPENDS()? > >> > >> I had the same thoughts, because softdeps are for optional module > >> dependencies, while in this case it's a hard dependency. Though, > >> I went with adding a softdep, simply because I saw no better option > >> available. > >> > >>>> This doesn't work on my side because depmod generates modules.dep > >>>> by symbol lookup instead of modinfo section. So softdep may be our > >>>> only > >>>> choice to add module dependency manually. I can accept the softdep > >>>> first, then make PM optional later. > >> > >> I also thought about making devfreq optional in the Lima driver, > >> which would make this additional softdep much more appropriate. > >> Though, I'm not really sure that's a good approach, because not > >> having working devfreq for Lima might actually cause issues on > >> some devices, such as increased power consumption. > >> > >> In other words, it might be better to have Lima probing fail if > >> devfreq can't be initialized, rather than having probing succeed > >> with no working devfreq. Basically, failed probing is obvious, > >> while a warning in the kernel log about no devfreq might easily > >> be overlooked, causing regressions on some devices. > >> > >>> It's still super fragile, and depends on the user not changing the > >>> policy. It should be solved in some other, more robust way. > >> > >> I see, but I'm not really sure how to make it more robust? In > >> the end, some user can blacklist the simple_ondemand governor > >> module, and we can't do much about it. > >> > >> Introducing harddeps alongside softdeps would make sense from > >> the design standpoint, but the amount of required changes wouldn't > >> be trivial at all, on various levels. > > > > After further investigation, it seems that the softdeps have > > already seen a fair amount of abuse for what they actually aren't > > intended, i.e. resolving hard dependencies. For example, have > > a look at the commit d5178578bcd4 (btrfs: directly call into > > crypto framework for checksumming) [1] and the lines containing > > MODULE_SOFTDEP() at the very end of fs/btrfs/super.c. [2] > > > > If a filesystem driver can rely on the abuse of softdeps, which > > admittedly are a bit fragile, I think we can follow the same > > approach, at least for now. > > > > With all that in mind, I think that accepting this patch, as well > > as the related Panfrost patch, [3] should be warranted. I'd keep > > investigating the possibility of introducing harddeps in form > > of MODULE_HARDDEP() and the related support in kmod project, > > similar to the already existing softdep support, [4] but that > > will inevitably take a lot of time, both for implementing it > > and for reaching various Linux distributions, which is another > > reason why accepting these patches seems reasonable. > > > > [1] > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5178578bcd4 > > [2] > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/super.c#n2593 > > [3] > > https://lore.kernel.org/dri-devel/4e1e00422a14db4e2a80870afb704405da16fd1b.1718655077.git.dsimic@manjaro.org/ > > [4] > > https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d
Hello Qiang, On 2024-06-26 03:11, Qiang Yu wrote: > On Wed, Jun 26, 2024 at 2:15 AM Dragan Simic <dsimic@manjaro.org> > wrote: >> >> Hello everyone, >> >> Just checking, any further thoughts about this patch? >> > I'm OK with this as a temp workaround because it's simple and do no > harm > even it's not perfect. If no other better suggestion for short term, > I'll submit > this at weekend. Thanks. Just as you described it, it's far from perfect, but it's still fine until there's a better solution, such as harddeps. I'll continue my research about the possibility for adding harddeps, which would hopefully replace quite a few instances of the softdep (ab)use. >> On 2024-06-18 21:22, Dragan Simic wrote: >> > On 2024-06-18 12:33, Dragan Simic wrote: >> >> On 2024-06-18 10:13, Maxime Ripard wrote: >> >>> On Tue, Jun 18, 2024 at 04:01:26PM GMT, Qiang Yu wrote: >> >>>> On Tue, Jun 18, 2024 at 12:33 PM Qiang Yu <yuq825@gmail.com> wrote: >> >>>> > >> >>>> > I see the problem that initramfs need to build a module dependency chain, >> >>>> > but lima does not call any symbol from simpleondemand governor module. >> >>>> > softdep module seems to be optional while our dependency is hard one, >> >>>> > can we just add MODULE_INFO(depends, _depends), or create a new >> >>>> > macro called MODULE_DEPENDS()? >> >> >> >> I had the same thoughts, because softdeps are for optional module >> >> dependencies, while in this case it's a hard dependency. Though, >> >> I went with adding a softdep, simply because I saw no better option >> >> available. >> >> >> >>>> This doesn't work on my side because depmod generates modules.dep >> >>>> by symbol lookup instead of modinfo section. So softdep may be our >> >>>> only >> >>>> choice to add module dependency manually. I can accept the softdep >> >>>> first, then make PM optional later. >> >> >> >> I also thought about making devfreq optional in the Lima driver, >> >> which would make this additional softdep much more appropriate. >> >> Though, I'm not really sure that's a good approach, because not >> >> having working devfreq for Lima might actually cause issues on >> >> some devices, such as increased power consumption. >> >> >> >> In other words, it might be better to have Lima probing fail if >> >> devfreq can't be initialized, rather than having probing succeed >> >> with no working devfreq. Basically, failed probing is obvious, >> >> while a warning in the kernel log about no devfreq might easily >> >> be overlooked, causing regressions on some devices. >> >> >> >>> It's still super fragile, and depends on the user not changing the >> >>> policy. It should be solved in some other, more robust way. >> >> >> >> I see, but I'm not really sure how to make it more robust? In >> >> the end, some user can blacklist the simple_ondemand governor >> >> module, and we can't do much about it. >> >> >> >> Introducing harddeps alongside softdeps would make sense from >> >> the design standpoint, but the amount of required changes wouldn't >> >> be trivial at all, on various levels. >> > >> > After further investigation, it seems that the softdeps have >> > already seen a fair amount of abuse for what they actually aren't >> > intended, i.e. resolving hard dependencies. For example, have >> > a look at the commit d5178578bcd4 (btrfs: directly call into >> > crypto framework for checksumming) [1] and the lines containing >> > MODULE_SOFTDEP() at the very end of fs/btrfs/super.c. [2] >> > >> > If a filesystem driver can rely on the abuse of softdeps, which >> > admittedly are a bit fragile, I think we can follow the same >> > approach, at least for now. >> > >> > With all that in mind, I think that accepting this patch, as well >> > as the related Panfrost patch, [3] should be warranted. I'd keep >> > investigating the possibility of introducing harddeps in form >> > of MODULE_HARDDEP() and the related support in kmod project, >> > similar to the already existing softdep support, [4] but that >> > will inevitably take a lot of time, both for implementing it >> > and for reaching various Linux distributions, which is another >> > reason why accepting these patches seems reasonable. >> > >> > [1] >> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5178578bcd4 >> > [2] >> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/super.c#n2593 >> > [3] >> > https://lore.kernel.org/dri-devel/4e1e00422a14db4e2a80870afb704405da16fd1b.1718655077.git.dsimic@manjaro.org/ >> > [4] >> > https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d
diff --git a/drivers/gpu/drm/lima/lima_drv.c b/drivers/gpu/drm/lima/lima_drv.c index 739c865b556f..10bce18b7c31 100644 --- a/drivers/gpu/drm/lima/lima_drv.c +++ b/drivers/gpu/drm/lima/lima_drv.c @@ -501,3 +501,4 @@ module_platform_driver(lima_platform_driver); MODULE_AUTHOR("Lima Project Developers"); MODULE_DESCRIPTION("Lima DRM Driver"); MODULE_LICENSE("GPL v2"); +MODULE_SOFTDEP("pre: governor_simpleondemand");
Lima DRM driver uses devfreq to perform DVFS, while using simple_ondemand devfreq governor by default. This causes driver initialization to fail on boot when simple_ondemand governor isn't built into the kernel statically, as a result of the missing module dependency and, consequently, the required governor module not being included in the initial ramdisk. Thus, let's mark simple_ondemand governor as a softdep for Lima, to have its kernel module included in the initial ramdisk. This is a rather longstanding issue that has forced distributions to build devfreq governors statically into their kernels, [1][2] or may have forced some users to introduce unnecessary workarounds. Having simple_ondemand marked as a softdep for Lima may not resolve this issue for all Linux distributions. In particular, it will remain unresolved for the distributions whose utilities for the initial ramdisk generation do not handle the available softdep information [3] properly yet. However, some Linux distributions already handle softdeps properly while generating their initial ramdisks, [4] and this is a prerequisite step in the right direction for the distributions that don't handle them properly yet. [1] https://gitlab.manjaro.org/manjaro-arm/packages/core/linux-pinephone/-/blob/6.7-megi/config?ref_type=heads#L5749 [2] https://gitlab.com/postmarketOS/pmaports/-/blob/7f64e287e7732c9eaa029653e73ca3d4ba1c8598/main/linux-postmarketos-allwinner/config-postmarketos-allwinner.aarch64#L4654 [3] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/commit/?id=49d8e0b59052999de577ab732b719cfbeb89504d [4] https://github.com/archlinux/mkinitcpio/commit/97ac4d37aae084a050be512f6d8f4489054668ad Cc: Philip Muller <philm@manjaro.org> Cc: Oliver Smith <ollieparanoid@postmarketos.org> Cc: Daniel Smith <danct12@disroot.org> Cc: stable@vger.kernel.org Fixes: 1996970773a3 ("drm/lima: Add optional devfreq and cooling device support") Signed-off-by: Dragan Simic <dsimic@manjaro.org> --- drivers/gpu/drm/lima/lima_drv.c | 1 + 1 file changed, 1 insertion(+)