On Fri, 22 Apr 2022 13:47:33 +0200 Pali Rohár <[email protected]> wrote:
> On Wednesday 02 March 2022 13:46:07 Marek Behún wrote: > > On Wed, 2 Mar 2022 12:47:58 +0100 > > Pali Rohár <[email protected]> wrote: > > > > > PCIe Mini CEM 2.1 spec added support for USB3.0 mode on MiniPCIe cards. > > > USB3.0 and PCIe share same pins and only one function can be active at the > > > same time. PCIe Mini CEM 2.1 spec says that determining function is > > > platform specific and spec does not define any dedicated pin which could > > > say if card is USB3.0-based or PCIe-based. > > > > > > Implement this platform specific decision (USB3.0 vs PCIe) for WWAN > > > MiniPCIe slot on Turris Omnia via U-Boot env variable "omnia_wwan_slot", > > > similarly like is implemented forced mode for MiniPCIe/mSATA slot via > > > "omnia_msata_slot" env variable. Value "usb3" for "omnia_wwan_slot" would > > > mean to set USB3.0 mode and value "pcie" original PCIe mode. > > > > > > A385 SoC on Turris Omnia has configurable fifth SerDes line (exported to > > > MiniPCIe WWAN slot with SIM card) either to USB3.0 or PCIe functionality, > > > so implementation of this new PCIe Mini CEM 2.1 feature is simple, by just > > > configuring SerDes to USB 3.0 mode. > > > > > > Other twos MiniPCIe slots on Turris Omnia do not have this new > > > functionality as their SerDes lines cannot be switched to USB3.0 > > > functionality. > > > > > > Note that A385 SoC does not have too many USB3.0 blocks, so activating > > > USB3.0 in MiniPCIe cause that one external USB3.0 USB-A port would loose > > > USB3.0 functionality and would be downgraded just to USB2.0. > > > > > > By default this MiniPCIe WWAN slot is in PCIe mode, like before. > > > > > > To set this MiniPCIe WWAN slot to USB3.0 mode, call U-Boot commands: > > > > > > => setenv omnia_wwan_slot usb3 > > > => saveenv > > > => reset > > > > > > Signed-off-by: Pali Rohár <[email protected]> > > > --- > > > board/CZ.NIC/turris_omnia/turris_omnia.c | 57 ++++++++++++++++++++++++ > > > 1 file changed, 57 insertions(+) > > > > > > diff --git a/board/CZ.NIC/turris_omnia/turris_omnia.c > > > b/board/CZ.NIC/turris_omnia/turris_omnia.c > > > index e2f4daa827ed..83cfc80d1930 100644 > > > --- a/board/CZ.NIC/turris_omnia/turris_omnia.c > > > +++ b/board/CZ.NIC/turris_omnia/turris_omnia.c > > > @@ -246,6 +246,22 @@ static bool omnia_detect_sata(const char *msata_slot) > > > return stsword & MSATA_IND_STSBIT ? true : false; > > > } > > > > > > +static bool omnia_detect_wwan_usb3(const char *wwan_slot) > > > +{ > > > + puts("WWAN slot configuration... "); > > > + > > > + if (wwan_slot && strcmp(wwan_slot, "usb3") == 0) { > > > + puts("USB3.0\n"); > > > + return true; > > > + } > > > + > > > + if (wwan_slot && strcmp(wwan_slot, "pcie") != 0) > > > + printf("unsupported env value '%s', fallback to... ", > > > wwan_slot); > > > > If I recall correctly, Linux' and U-Boot's code style (in contrast to > > TF-A) normally wants > > if (expr) instead of if (expr != 0) > > and > > if (!expr) instead of if (expr == 0) > > I guess that this applies for functions which return boolean value. And > not for strcmp() function which is not failure expression. But instead > it returns comparison value. Again, this was an unimportant nitpick from me, feel free to ignore this. But since you replied, I shall entertain you with an opinion I have to share. I am sure that I remember people from TF-A requesting to use (x == 0) or (x != 0), while people from Linux requesting (x) or (!x), not only for functions which return boolean value. I am not sure now for what kind of function it may have been exactly, but I think it was someting like err = func(); if (err == 0) .. and the request was to change it to if (!err) I guess that functions which return 0 on success and negative error code on failure may be considered returning "boolean" in a sense of success/failure boolean. But anyway if seems that in the usage of strcmp(), Linux uses both variants, although the one with the comparison operator is used a little bit less: $ git grep 'strcmp' | wc -l 6971 $ git grep 'strcmp.* [=!]= 0' | wc -l 2100 Mostly the strcmp() function is used to determine whether two strings are equal or not, which is a binary/boolean decision, and so I prefer to check the result as such. But strcmp() can be also used to compare strings for sorting, and that is the case where ==, < and > operators would make sense to me. Again, feel free to ignore, since this is a matter of personal preference. Marek
