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    SubjectRe: [PATCH v7 10/24] wfx: add fwio.c/fwio.h
    Date
    Jérôme Pouiller <jerome.pouiller@silabs.com> writes:

    > On Friday 1 October 2021 18:08:32 CEST Pali Rohár wrote:
    >> On Friday 01 October 2021 17:09:41 Jérôme Pouiller wrote:
    >> > On Friday 1 October 2021 13:58:38 CEST Kalle Valo wrote:
    >> > > Jerome Pouiller <Jerome.Pouiller@silabs.com> writes:
    >> > >
    >> > > > From: Jérôme Pouiller <jerome.pouiller@silabs.com>
    >> > > >
    >> > > > Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
    >> > >
    >> > > [...]
    >> > >
    >> > > > +static int get_firmware(struct wfx_dev *wdev, u32 keyset_chip,
    >> > > > + const struct firmware **fw, int *file_offset)
    >> > > > +{
    >> > > > + int keyset_file;
    >> > > > + char filename[256];
    >> > > > + const char *data;
    >> > > > + int ret;
    >> > > > +
    >> > > > + snprintf(filename, sizeof(filename), "%s_%02X.sec",
    >> > > > + wdev->pdata.file_fw, keyset_chip);
    >> > > > + ret = firmware_request_nowarn(fw, filename, wdev->dev);
    >> > > > + if (ret) {
    >> > > > + dev_info(wdev->dev, "can't load %s, falling back to %s.sec\n",
    >> > > > + filename, wdev->pdata.file_fw);
    >> > > > + snprintf(filename, sizeof(filename), "%s.sec",
    >> > > > + wdev->pdata.file_fw);
    >> > > > + ret = request_firmware(fw, filename, wdev->dev);
    >> > > > + if (ret) {
    >> > > > + dev_err(wdev->dev, "can't load %s\n", filename);
    >> > > > + *fw = NULL;
    >> > > > + return ret;
    >> > > > + }
    >> > > > + }
    >> > >
    >> > > How is this firmware file loading supposed to work? If I'm reading the
    >> > > code right, the driver tries to load file "wfm_wf200_??.sec" but in
    >> > > linux-firmware the file is silabs/wfm_wf200_C0.sec:
    >> > >
    >> > > https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/silabs
    >> > >
    >> > > That can't work automatically, unless I'm missing something of course.
    >> >
    >> > The firmware are signed. "C0" is the key used to sign this firmware. This
    >> > key must match with the key burned into the chip. Fortunately, the driver
    >> > is able to read the key accepted by the chip and automatically choose the
    >> > right firmware.
    >> >
    >> > We could imagine to add a attribute in the DT to choose the firmware to
    >> > load. However, it would be a pity to have to specify it manually whereas
    >> > the driver is able to detect it automatically.
    >> >
    >> > Currently, the only possible key is C0. However, it exists some internal
    >> > parts with other keys. In addition, it is theoretically possible to ask
    >> > to Silabs to burn parts with a specific key in order to improve security
    >> > of a product.
    >> >
    >> > Obviously, for now, this feature mainly exists for the Silabs firmware
    >> > developers who have to work with other keys.
    >> >
    >> > > Also I would prefer to use directory name as the driver name wfx, but I
    >> > > guess silabs is also doable.
    >> >
    >> > I have no opinion.
    >> >
    >> >
    >> > > Also I'm not seeing the PDS files in linux-firmware. The idea is that
    >> > > when user installs an upstream kernel and the linux-firmware everything
    >> > > will work automatically, without any manual file installations.
    >> >
    >> > WF200 is just a chip. Someone has to design an antenna before to be able
    >> > to use.
    >> >
    >> > However, we have evaluation boards that have antennas and corresponding
    >> > PDS files[1]. Maybe linux-firmware should include the PDS for these boards
    >>
    >> So chip vendor provides firmware and card vendor provides PDS files.
    >
    > Exactly.
    >
    >> In
    >> my opinion all files should go into linux-firmware repository. If Silabs
    >> has PDS files for its devel boards (which are basically cards) then I
    >> think these files should go also into linux-firmware repository.
    >>
    >> And based on some parameter, driver should load correct PDS file. Seems
    >> like DT can be a place where to put something which indicates which PDS
    >> file should be used.
    >>
    >> But should be in DT directly name of PDS file? Or should be in DT just
    >> additional compatible string with card vendor name and then in driver
    >> itself should be mapping table from compatible string to filename? I do
    >> not know what is better.
    >
    > The DT already accepts the attribute silabs,antenna-config-file (see
    > patch #2).
    >
    > I think that linux-firmware repository will reject the pds files if
    > no driver in the kernel directly point to it. Else how to detect
    > orphans?

    This (linux-firmware rejecting files) is news to me, do you have any
    pointers?

    > So, I think it is slightly better to use a mapping table.

    Not following you here.

    --
    https://patchwork.kernel.org/project/linux-wireless/list/

    https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

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