Hi Padmarao
On Tue, 9 Jun 2026 at 13:10, Padmarao Begari <[email protected]> wrote: > > The tpm-rng driver calls tpm_get_random() without first ensuring the > TPM device is opened and started. When systemd-boot or fdt_fixup_kaslr > triggers an RNG read early in boot, the TPM2 device hasn't been > initialized yet, causing the command to fail: Is systemd_boot called via EFI? If so the TPM should be up already. About fdt_fixup_kaslr(), why do you need this? We specifically clear the kaslr-seed when booting via EFI and EFI_RNG is installed, since the kernel ignores it. Thanks /Ilias > > tpm-rng tpm-rng: dm_rng_read failed: -1 > > Fix this by calling tpm_auto_start() on the parent TPM device before > tpm_get_random(). This ensures the TPM is initialized before use. > > Fixes: e67ffb5aa5ab ("tpm: rng: Add driver model interface for TPM RNG > device") > Signed-off-by: Padmarao Begari <[email protected]> > --- > drivers/rng/tpm_rng.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/rng/tpm_rng.c b/drivers/rng/tpm_rng.c > index 1a5e9e2e4b4..374e0ac1ff8 100644 > --- a/drivers/rng/tpm_rng.c > +++ b/drivers/rng/tpm_rng.c > @@ -4,12 +4,20 @@ > */ > > #include <dm.h> > +#include <log.h> > #include <rng.h> > #include <tpm_api.h> > > static int rng_tpm_random_read(struct udevice *dev, void *data, size_t count) > { > - return tpm_get_random(dev_get_parent(dev), data, count); > + struct udevice *tpm_dev = dev_get_parent(dev); > + u32 rc; > + > + rc = tpm_auto_start(tpm_dev); > + if (rc) > + return log_msg_ret("start", -EIO); > + > + return tpm_get_random(tpm_dev, data, count); > } > > static const struct dm_rng_ops tpm_rng_ops = { > -- > 2.34.1 >
