Re: [U-Boot] [PATCH v3 025/108] x86: tpl: Add a fake PCI bus
On Mon, Oct 28, 2019 at 3:12 PM Bin Meng wrote: > > On Mon, Oct 21, 2019 at 11:40 AM Simon Glass wrote: > > > > In TPL we try to minimise code size so do not include the PCI subsystem. > > We can use fixed BARs and drivers can directly program the devices that > > they need. > > > > However we do need to bind the devices on the PCI bus and without PCI this > > does not ordinarily happen. As a work-around, define a fake PCI bus which > > does this binding, but no other PCI operations. This is a convenient way > > to ensure that we can use the same device tree for TPL, SPL and U-Boot > > proper: > > > >TPL- CONFIG_TPL_PCI is not set (no auto-config, fake PCI bus) > >SPL- CONFIG_SPL_PCI is set (no auto-config but with real PCI bus) > >U-Boot - CONFIG_PCI is set (full auto-config after relocation) > > > > Signed-off-by: Simon Glass > > --- > > > > Changes in v3: > > - Fix 'autoallocation' typo > > - Improve wording in commit message > > > > Changes in v2: None > > > > arch/x86/lib/tpl.c | 25 + > > 1 file changed, 25 insertions(+) > > > > Reviewed-by: Bin Meng applied to u-boot-x86, thanks! ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] [PATCH v3 025/108] x86: tpl: Add a fake PCI bus
On Mon, Oct 21, 2019 at 11:40 AM Simon Glass wrote: > > In TPL we try to minimise code size so do not include the PCI subsystem. > We can use fixed BARs and drivers can directly program the devices that > they need. > > However we do need to bind the devices on the PCI bus and without PCI this > does not ordinarily happen. As a work-around, define a fake PCI bus which > does this binding, but no other PCI operations. This is a convenient way > to ensure that we can use the same device tree for TPL, SPL and U-Boot > proper: > >TPL- CONFIG_TPL_PCI is not set (no auto-config, fake PCI bus) >SPL- CONFIG_SPL_PCI is set (no auto-config but with real PCI bus) >U-Boot - CONFIG_PCI is set (full auto-config after relocation) > > Signed-off-by: Simon Glass > --- > > Changes in v3: > - Fix 'autoallocation' typo > - Improve wording in commit message > > Changes in v2: None > > arch/x86/lib/tpl.c | 25 + > 1 file changed, 25 insertions(+) > Reviewed-by: Bin Meng ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] [PATCH v3 025/108] x86: tpl: Add a fake PCI bus
Hi Andy, On Tue, 22 Oct 2019 at 02:19, Andy Shevchenko wrote: > > On Tue, Oct 22, 2019 at 1:54 AM Simon Glass wrote: > > On Mon, 21 Oct 2019 at 01:52, Andy Shevchenko > > wrote: > > > On Mon, Oct 21, 2019 at 7:24 AM Simon Glass wrote: > > > > PCI(e) bus is present in a lot of SoCs (not exclusively x86). Perhaps > > > better idea is to have something like lib/pci.c with minimum support > > > for PCI type 1 and probably PCI type 2 accessors and other very basic > > > functions. > > > > I don't know of any use case for PCI in TPL on other platforms. > > > > x86 is I think unique in that it requires PCI to do anything. > > I don't think so. PCI is a core part of the SoC, indeed, though what > exactly do we need from it here? IO accessors to PCI configuration > space? I mean that on other SoCs I am familiar with you can access peripherals through memory-mapped I/O. On x86 so far as I am aware you can't see any peripheral without doing some PCI config. Therefore PCI is 'more core' on x86 than others. For example on an Nvidia chip I am familiar with, you can do everything except enable the PCI network chip, which you wouldn't do in TPL. > > > For > > other platforms I am familiar with they can boot a fair way without > > it. > > Perhaps we may achieve the same here? > > > I do want to avoid the premature-optimisation problem, i.e. inventing > > new use cases that no one uses. The only thing we really know right > > now is that we need this for newer x86 platforms. Regards, Simon ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] [PATCH v3 025/108] x86: tpl: Add a fake PCI bus
On Tue, Oct 22, 2019 at 1:54 AM Simon Glass wrote: > On Mon, 21 Oct 2019 at 01:52, Andy Shevchenko > wrote: > > On Mon, Oct 21, 2019 at 7:24 AM Simon Glass wrote: > > PCI(e) bus is present in a lot of SoCs (not exclusively x86). Perhaps > > better idea is to have something like lib/pci.c with minimum support > > for PCI type 1 and probably PCI type 2 accessors and other very basic > > functions. > > I don't know of any use case for PCI in TPL on other platforms. > > x86 is I think unique in that it requires PCI to do anything. I don't think so. PCI is a core part of the SoC, indeed, though what exactly do we need from it here? IO accessors to PCI configuration space? > For > other platforms I am familiar with they can boot a fair way without > it. Perhaps we may achieve the same here? > I do want to avoid the premature-optimisation problem, i.e. inventing > new use cases that no one uses. The only thing we really know right > now is that we need this for newer x86 platforms. -- With Best Regards, Andy Shevchenko ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] [PATCH v3 025/108] x86: tpl: Add a fake PCI bus
Hi Andy, On Mon, 21 Oct 2019 at 01:52, Andy Shevchenko wrote: > > On Mon, Oct 21, 2019 at 7:24 AM Simon Glass wrote: > > > > In TPL we try to minimise code size so do not include the PCI subsystem. > > We can use fixed BARs and drivers can directly program the devices that > > they need. > > > > However we do need to bind the devices on the PCI bus and without PCI this > > does not ordinarily happen. As a work-around, define a fake PCI bus which > > does this binding, but no other PCI operations. This is a convenient way > > to ensure that we can use the same device tree for TPL, SPL and U-Boot > > proper: > > > >TPL- CONFIG_TPL_PCI is not set (no auto-config, fake PCI bus) > >SPL- CONFIG_SPL_PCI is set (no auto-config but with real PCI bus) > >U-Boot - CONFIG_PCI is set (full auto-config after relocation) > > PCI(e) bus is present in a lot of SoCs (not exclusively x86). Perhaps > better idea is to have something like lib/pci.c with minimum support > for PCI type 1 and probably PCI type 2 accessors and other very basic > functions. I don't know of any use case for PCI in TPL on other platforms. x86 is I think unique in that it requires PCI to do anything. For other platforms I am familiar with they can boot a fair way without it. I do want to avoid the premature-optimisation problem, i.e. inventing new use cases that no one uses. The only thing we really know right now is that we need this for newer x86 platforms. Regards, Simon ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] [PATCH v3 025/108] x86: tpl: Add a fake PCI bus
On Mon, Oct 21, 2019 at 7:24 AM Simon Glass wrote: > > In TPL we try to minimise code size so do not include the PCI subsystem. > We can use fixed BARs and drivers can directly program the devices that > they need. > > However we do need to bind the devices on the PCI bus and without PCI this > does not ordinarily happen. As a work-around, define a fake PCI bus which > does this binding, but no other PCI operations. This is a convenient way > to ensure that we can use the same device tree for TPL, SPL and U-Boot > proper: > >TPL- CONFIG_TPL_PCI is not set (no auto-config, fake PCI bus) >SPL- CONFIG_SPL_PCI is set (no auto-config but with real PCI bus) >U-Boot - CONFIG_PCI is set (full auto-config after relocation) PCI(e) bus is present in a lot of SoCs (not exclusively x86). Perhaps better idea is to have something like lib/pci.c with minimum support for PCI type 1 and probably PCI type 2 accessors and other very basic functions. -- With Best Regards, Andy Shevchenko ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
