| Message ID | 1437670290-25660-1-git-send-email-swarren@wwwdotorg.org |
|---|---|
| State | Accepted |
| Delegated to: | Tom Warren |
| Headers | show |
Hi, On 23 July 2015 at 10:51, Stephen Warren <swarren@wwwdotorg.org> wrote: > From: Thierry Reding <treding@nvidia.com> > > Signed-off-by: Thierry Reding <treding@nvidia.com> > Signed-off-by: Tom Warren <twarren@nvidia.com> > Signed-off-by: Stephen Warren <swarren@nvidia.com> > --- > Simon, > > When Thierry first posted this patch, you responded: > >> > + parent = fdt_parent_offset(blob, node); >> >> This function is very slow as it must scan the whole tree. Can we >> instead pass in the parent node? > > I don't think that's possible in general. This function is called from > fdtdec_get_addr(), and it's easy to find call sites of that function that > don't have the parent node available. IIRC, the first couple of example I > found scan the DT for a node with a certain compatible value, or look up > nodes via aliases, rather than being called while parsing the DT in a > top-down tree-like fashion, where the parent node is easily available. I > didn't do an exhaustive search after I found a few problematic cases. > >> Also, how about (in addition) a >> version of this function that works for devices? Like: >> >> device_get_addr_size(struct udevice *dev, ...) >> >> so that it can handle this for you. > > That sounds like a separate patch? Yes, but I think we should get it in there so that people don't start using this (wildly inefficient) function when they don't need to. I think by passing in the parent node we force people to think about the cost. Yes the driver model function can be a separate patch, but let's get it in at about the same time. We have dev_get_addr() so could have dev_get_addr_size(). > > Equally, I see that struct udevice contains an of_offset field, but no > parent_of_offset or similar. There is a struct udevice *parent though; > is the struct udevice hierarchy guaranteed to 100% match the DT > hierarchy? I know this isn't necessarily guaranteed in Linux's device > model for example. Yes it is 100% guaranteed, so dev->parent->of_offset will do the right thing. > > As such, this patch seems OK to me as-is. > --- > lib/fdtdec.c | 56 ++++++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 36 insertions(+), 20 deletions(-) > > diff --git a/lib/fdtdec.c b/lib/fdtdec.c > index 9c6b3619da24..56e72eafaade 100644 > --- a/lib/fdtdec.c > +++ b/lib/fdtdec.c > @@ -88,29 +88,45 @@ const char *fdtdec_get_compatible(enum fdt_compat_id id) > fdt_addr_t fdtdec_get_addr_size(const void *blob, int node, > const char *prop_name, fdt_size_t *sizep) > { > - const fdt_addr_t *cell; > - int len; > + const fdt32_t *ptr, *end; > + int parent, na, ns, len; > + fdt_addr_t addr; > > debug("%s: %s: ", __func__, prop_name); > - cell = fdt_getprop(blob, node, prop_name, &len); > - if (cell && ((!sizep && len == sizeof(fdt_addr_t)) || > - len == sizeof(fdt_addr_t) * 2)) { > - fdt_addr_t addr = fdt_addr_to_cpu(*cell); > - if (sizep) { > - const fdt_size_t *size; > - > - size = (fdt_size_t *)((char *)cell + > - sizeof(fdt_addr_t)); > - *sizep = fdt_size_to_cpu(*size); > - debug("addr=%08lx, size=%llx\n", > - (ulong)addr, (u64)*sizep); > - } else { > - debug("%08lx\n", (ulong)addr); > - } > - return addr; > + > + parent = fdt_parent_offset(blob, node); > + if (parent < 0) { > + debug("(no parent found)\n"); > + return FDT_ADDR_T_NONE; > } > - debug("(not found)\n"); > - return FDT_ADDR_T_NONE; > + > + na = fdt_address_cells(blob, parent); > + ns = fdt_size_cells(blob, parent); > + > + ptr = fdt_getprop(blob, node, prop_name, &len); > + if (!ptr) { > + debug("(not found)\n"); > + return FDT_ADDR_T_NONE; > + } > + > + end = ptr + len / sizeof(*ptr); > + > + if (ptr + na + ns > end) { > + debug("(not enough data: expected %d bytes, got %d bytes)\n", > + (na + ns) * 4, len); > + return FDT_ADDR_T_NONE; > + } > + > + addr = fdtdec_get_number(ptr, na); > + > + if (sizep) { > + *sizep = fdtdec_get_number(ptr + na, ns); > + debug("addr=%pa, size=%pa\n", &addr, sizep); > + } else { > + debug("%pa\n", &addr); > + } > + > + return addr; > } > > fdt_addr_t fdtdec_get_addr(const void *blob, int node, > -- > 1.9.1 > Regards, SImon
Hi, On 27 July 2015 at 11:13, Simon Glass <sjg@chromium.org> wrote: > Hi, > > On 23 July 2015 at 10:51, Stephen Warren <swarren@wwwdotorg.org> wrote: >> From: Thierry Reding <treding@nvidia.com> >> >> Signed-off-by: Thierry Reding <treding@nvidia.com> >> Signed-off-by: Tom Warren <twarren@nvidia.com> >> Signed-off-by: Stephen Warren <swarren@nvidia.com> >> --- >> Simon, >> >> When Thierry first posted this patch, you responded: >> >>> > + parent = fdt_parent_offset(blob, node); >>> >>> This function is very slow as it must scan the whole tree. Can we >>> instead pass in the parent node? >> >> I don't think that's possible in general. This function is called from >> fdtdec_get_addr(), and it's easy to find call sites of that function that >> don't have the parent node available. IIRC, the first couple of example I >> found scan the DT for a node with a certain compatible value, or look up >> nodes via aliases, rather than being called while parsing the DT in a >> top-down tree-like fashion, where the parent node is easily available. I >> didn't do an exhaustive search after I found a few problematic cases. >> >>> Also, how about (in addition) a >>> version of this function that works for devices? Like: >>> >>> device_get_addr_size(struct udevice *dev, ...) >>> >>> so that it can handle this for you. >> >> That sounds like a separate patch? > > Yes, but I think we should get it in there so that people don't start > using this (wildly inefficient) function when they don't need to. I > think by passing in the parent node we force people to think about the > cost. > > Yes the driver model function can be a separate patch, but let's get > it in at about the same time. We have dev_get_addr() so could have > dev_get_addr_size(). > >> >> Equally, I see that struct udevice contains an of_offset field, but no >> parent_of_offset or similar. There is a struct udevice *parent though; >> is the struct udevice hierarchy guaranteed to 100% match the DT >> hierarchy? I know this isn't necessarily guaranteed in Linux's device >> model for example. > > Yes it is 100% guaranteed, so dev->parent->of_offset will do the right thing. > >> >> As such, this patch seems OK to me as-is. >> --- >> lib/fdtdec.c | 56 ++++++++++++++++++++++++++++++++++++-------------------- >> 1 file changed, 36 insertions(+), 20 deletions(-) >> This patch has been applied. I'm going to post a revert of this patch. Please can you take a look at the comments above? In particular this function is called from dev_get_addr() which is a core driver model function. It needs to be fast - and in fact dev_get_addr() already has access to the parent node. Also looking a bit closer this patch does a lot more than 'fix it for 64-bit'. A commit message would be useful to explain what problems it is fixing, etc. Another point is that fdt_addr_t and fdt_size_t are supposed to match the address size used in the device tree. Is that not the case with Tegra210? >> diff --git a/lib/fdtdec.c b/lib/fdtdec.c >> index 9c6b3619da24..56e72eafaade 100644 >> --- a/lib/fdtdec.c >> +++ b/lib/fdtdec.c >> @@ -88,29 +88,45 @@ const char *fdtdec_get_compatible(enum fdt_compat_id id) >> fdt_addr_t fdtdec_get_addr_size(const void *blob, int node, >> const char *prop_name, fdt_size_t *sizep) >> { >> - const fdt_addr_t *cell; >> - int len; >> + const fdt32_t *ptr, *end; >> + int parent, na, ns, len; >> + fdt_addr_t addr; >> >> debug("%s: %s: ", __func__, prop_name); >> - cell = fdt_getprop(blob, node, prop_name, &len); >> - if (cell && ((!sizep && len == sizeof(fdt_addr_t)) || >> - len == sizeof(fdt_addr_t) * 2)) { >> - fdt_addr_t addr = fdt_addr_to_cpu(*cell); >> - if (sizep) { >> - const fdt_size_t *size; >> - >> - size = (fdt_size_t *)((char *)cell + >> - sizeof(fdt_addr_t)); >> - *sizep = fdt_size_to_cpu(*size); >> - debug("addr=%08lx, size=%llx\n", >> - (ulong)addr, (u64)*sizep); >> - } else { >> - debug("%08lx\n", (ulong)addr); >> - } >> - return addr; >> + >> + parent = fdt_parent_offset(blob, node); >> + if (parent < 0) { >> + debug("(no parent found)\n"); >> + return FDT_ADDR_T_NONE; >> } >> - debug("(not found)\n"); >> - return FDT_ADDR_T_NONE; >> + >> + na = fdt_address_cells(blob, parent); >> + ns = fdt_size_cells(blob, parent); >> + >> + ptr = fdt_getprop(blob, node, prop_name, &len); >> + if (!ptr) { >> + debug("(not found)\n"); >> + return FDT_ADDR_T_NONE; >> + } >> + >> + end = ptr + len / sizeof(*ptr); >> + >> + if (ptr + na + ns > end) { >> + debug("(not enough data: expected %d bytes, got %d bytes)\n", >> + (na + ns) * 4, len); >> + return FDT_ADDR_T_NONE; >> + } >> + >> + addr = fdtdec_get_number(ptr, na); >> + >> + if (sizep) { >> + *sizep = fdtdec_get_number(ptr + na, ns); >> + debug("addr=%pa, size=%pa\n", &addr, sizep); >> + } else { >> + debug("%pa\n", &addr); >> + } >> + >> + return addr; >> } >> >> fdt_addr_t fdtdec_get_addr(const void *blob, int node, >> -- >> 1.9.1 >> Regards, Simon
On Sun, Aug 02, 2015 at 03:27:53PM -0600, Simon Glass wrote: > Hi, > > On 27 July 2015 at 11:13, Simon Glass <sjg@chromium.org> wrote: > > Hi, > > > > On 23 July 2015 at 10:51, Stephen Warren <swarren@wwwdotorg.org> wrote: > >> From: Thierry Reding <treding@nvidia.com> > >> > >> Signed-off-by: Thierry Reding <treding@nvidia.com> > >> Signed-off-by: Tom Warren <twarren@nvidia.com> > >> Signed-off-by: Stephen Warren <swarren@nvidia.com> > >> --- > >> Simon, > >> > >> When Thierry first posted this patch, you responded: > >> > >>> > + parent = fdt_parent_offset(blob, node); > >>> > >>> This function is very slow as it must scan the whole tree. Can we > >>> instead pass in the parent node? > >> > >> I don't think that's possible in general. This function is called from > >> fdtdec_get_addr(), and it's easy to find call sites of that function that > >> don't have the parent node available. IIRC, the first couple of example I > >> found scan the DT for a node with a certain compatible value, or look up > >> nodes via aliases, rather than being called while parsing the DT in a > >> top-down tree-like fashion, where the parent node is easily available. I > >> didn't do an exhaustive search after I found a few problematic cases. > >> > >>> Also, how about (in addition) a > >>> version of this function that works for devices? Like: > >>> > >>> device_get_addr_size(struct udevice *dev, ...) > >>> > >>> so that it can handle this for you. > >> > >> That sounds like a separate patch? > > > > Yes, but I think we should get it in there so that people don't start > > using this (wildly inefficient) function when they don't need to. I > > think by passing in the parent node we force people to think about the > > cost. > > > > Yes the driver model function can be a separate patch, but let's get > > it in at about the same time. We have dev_get_addr() so could have > > dev_get_addr_size(). > > > >> > >> Equally, I see that struct udevice contains an of_offset field, but no > >> parent_of_offset or similar. There is a struct udevice *parent though; > >> is the struct udevice hierarchy guaranteed to 100% match the DT > >> hierarchy? I know this isn't necessarily guaranteed in Linux's device > >> model for example. > > > > Yes it is 100% guaranteed, so dev->parent->of_offset will do the right thing. > > > >> > >> As such, this patch seems OK to me as-is. > >> --- > >> lib/fdtdec.c | 56 ++++++++++++++++++++++++++++++++++++-------------------- > >> 1 file changed, 36 insertions(+), 20 deletions(-) > >> > > This patch has been applied. I'm going to post a revert of this patch. > Please can you take a look at the comments above? In particular this > function is called from dev_get_addr() which is a core driver model > function. It needs to be fast - and in fact dev_get_addr() already has > access to the parent node. Perhaps this could be fixed by doing passing in the parent as an optional argument and then do something like this: if (parent < 0) { parent = fdt_parent_offset(blob, node); if (parent < 0) { ... } } In that case callers that have access to the parent node already can pass it in, but others can simply pass in -1 and have the function do the lookup. > Also looking a bit closer this patch does a lot more than 'fix it for > 64-bit'. A commit message would be useful to explain what problems it > is fixing, etc. > > Another point is that fdt_addr_t and fdt_size_t are supposed to match > the address size used in the device tree. Is that not the case with > Tegra210? You can't assume that #address-cells and #size-cells will be 2 for all 64-bit platforms. Some may well go with #address-cells = 1 and #size- cells = 1, and I've seen others do #address-cells = 2 and #size-cells = 1. All of these combinations are perfectly valid. As such, fdt_addr_t and fdt_size_t make sense only if they are the maximum that the architecture can support. Even so an address could technically be larger than that, if it's behind a translated bus, for example. So what this does is really fix parsing of address and size cells in the general case, though it would still fail for values of #address-cells or #size-cells bigger than 2 (because we don't have a datatype that would be able to contain such large values). Note that there's also still a corner case that this doesn't handle. The DT specification states, if I remember correctly, that #address-cells and #size-cells are inherited. That means with the current code we will wrongly parse something like this: / { ... #address-cells = <1>; #size-cells = <1>; ... bus@XXXXXXXX { ... device@XXXXXXXX { ... reg = <0xXXXXXXXX 0x1000>; ... }; ... }; ... }; According to the DT specification the bus@XXXXXXXX node would inherit #address-cells = <1> and #size-cells = <1> from the root node. However with libfdt what really happens is that since bus@XXXXXXXX does not have either property it will default to 2 in both cases. I'm not sure if this really is a problem. Typically nodes are not nested that deeply, or if they are then, typically, they explicitly contain #address-cells and #size-cells properties. Thierry
On 08/04/2015 08:26 AM, Thierry Reding wrote: ... [ discussion of new fdtdec_get_addr_size() implementation] > So what this does is really fix parsing of address and size cells in the > general case, though it would still fail for values of #address-cells or > #size-cells bigger than 2 (because we don't have a datatype that would > be able to contain such large values). > > Note that there's also still a corner case that this doesn't handle. The > DT specification states, if I remember correctly, that #address-cells > and #size-cells are inherited. That means with the current code we will > wrongly parse something like this: > > / { > ... > #address-cells = <1>; > #size-cells = <1>; > ... > bus@XXXXXXXX { > ... > device@XXXXXXXX { > ... > reg = <0xXXXXXXXX 0x1000>; > ... > }; > ... > }; > ... > }; > > According to the DT specification the bus@XXXXXXXX node would inherit > #address-cells = <1> and #size-cells = <1> from the root node. However > with libfdt what really happens is that since bus@XXXXXXXX does not have > either property it will default to 2 in both cases. I'm not sure if this > really is a problem. Typically nodes are not nested that deeply, or if > they are then, typically, they explicitly contain #address-cells and > #size-cells properties. I don't think #address-cells/#size-cells do actually get inherited. Admittedly some other properties (e.g. interrupt-parent) do, but according to: https://lists.ozlabs.org/pipermail/linuxppc-dev/2008-January/049113.html [PATCH] powerpc: #address-cells & #size-cells properties not inherited ... and my vague memory, these two don't. You can search Google for e.g. "#address-cells inherited" and find a number of similar assertions.
On Tue, Aug 04, 2015 at 09:23:27AM -0600, Stephen Warren wrote: > On 08/04/2015 08:26 AM, Thierry Reding wrote: > ... [ discussion of new fdtdec_get_addr_size() implementation] > >So what this does is really fix parsing of address and size cells in the > >general case, though it would still fail for values of #address-cells or > >#size-cells bigger than 2 (because we don't have a datatype that would > >be able to contain such large values). > > > >Note that there's also still a corner case that this doesn't handle. The > >DT specification states, if I remember correctly, that #address-cells > >and #size-cells are inherited. That means with the current code we will > >wrongly parse something like this: > > > > / { > > ... > > #address-cells = <1>; > > #size-cells = <1>; > > ... > > bus@XXXXXXXX { > > ... > > device@XXXXXXXX { > > ... > > reg = <0xXXXXXXXX 0x1000>; > > ... > > }; > > ... > > }; > > ... > > }; > > > >According to the DT specification the bus@XXXXXXXX node would inherit > >#address-cells = <1> and #size-cells = <1> from the root node. However > >with libfdt what really happens is that since bus@XXXXXXXX does not have > >either property it will default to 2 in both cases. I'm not sure if this > >really is a problem. Typically nodes are not nested that deeply, or if > >they are then, typically, they explicitly contain #address-cells and > >#size-cells properties. > > I don't think #address-cells/#size-cells do actually get inherited. > Admittedly some other properties (e.g. interrupt-parent) do, but according > to: > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2008-January/049113.html > [PATCH] powerpc: #address-cells & #size-cells properties not inherited > > ... and my vague memory, these two don't. > > You can search Google for e.g. "#address-cells inherited" and find a number > of similar assertions. Okay, that's good. It means there's not even a corner case. =) Thierry
diff --git a/lib/fdtdec.c b/lib/fdtdec.c index 9c6b3619da24..56e72eafaade 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -88,29 +88,45 @@ const char *fdtdec_get_compatible(enum fdt_compat_id id) fdt_addr_t fdtdec_get_addr_size(const void *blob, int node, const char *prop_name, fdt_size_t *sizep) { - const fdt_addr_t *cell; - int len; + const fdt32_t *ptr, *end; + int parent, na, ns, len; + fdt_addr_t addr; debug("%s: %s: ", __func__, prop_name); - cell = fdt_getprop(blob, node, prop_name, &len); - if (cell && ((!sizep && len == sizeof(fdt_addr_t)) || - len == sizeof(fdt_addr_t) * 2)) { - fdt_addr_t addr = fdt_addr_to_cpu(*cell); - if (sizep) { - const fdt_size_t *size; - - size = (fdt_size_t *)((char *)cell + - sizeof(fdt_addr_t)); - *sizep = fdt_size_to_cpu(*size); - debug("addr=%08lx, size=%llx\n", - (ulong)addr, (u64)*sizep); - } else { - debug("%08lx\n", (ulong)addr); - } - return addr; + + parent = fdt_parent_offset(blob, node); + if (parent < 0) { + debug("(no parent found)\n"); + return FDT_ADDR_T_NONE; } - debug("(not found)\n"); - return FDT_ADDR_T_NONE; + + na = fdt_address_cells(blob, parent); + ns = fdt_size_cells(blob, parent); + + ptr = fdt_getprop(blob, node, prop_name, &len); + if (!ptr) { + debug("(not found)\n"); + return FDT_ADDR_T_NONE; + } + + end = ptr + len / sizeof(*ptr); + + if (ptr + na + ns > end) { + debug("(not enough data: expected %d bytes, got %d bytes)\n", + (na + ns) * 4, len); + return FDT_ADDR_T_NONE; + } + + addr = fdtdec_get_number(ptr, na); + + if (sizep) { + *sizep = fdtdec_get_number(ptr + na, ns); + debug("addr=%pa, size=%pa\n", &addr, sizep); + } else { + debug("%pa\n", &addr); + } + + return addr; } fdt_addr_t fdtdec_get_addr(const void *blob, int node,