On Mon, Oct 29, 2018 at 12:52:17PM -0700, Tadeusz Struk wrote: > Currently to read a response from the TPM device an application needs > provide big enough buffer for the whole response and read it in one go. > The application doesn't know how big the response it beforehand so it > always needs to maintain a 4K buffer and read the max (4K). > In case if the user of the TSS library doesn't provide big enough > buffer the TCTI spec says that the library should set the required > size and return TSS2_TCTI_RC_INSUFFICIENT_BUFFER error code so that the > application could allocate a bigger buffer and call receive again. > To make it possible in the TSS library, this requires being able to do > partial reads from the driver. > The library would read the 10 bytes header first to get the actual size > of the response from the header, and then read the rest of the response. > This patch adds support for partial reads, i.e. the user can read the > response in one or multiple reads, until the whole response is consumed. > The user can also read only part of the response and ignore > the rest by issuing a new write to send a new command. You don't explain what the commit does at all. > The usecase is implemented in this TSS commit: > https://github.com/tpm2-software/tpm2-tss/commit/ce982f67a67dc08e24683d30b05800648d8a264c We do not want this as part of the commit message. You should place this in the beginning of the diffstat section. > > Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxx> > --- > Changes in v2: > - Allow writes after only partial response is consumed to maintain > backwords compatibility. > --- > drivers/char/tpm/tpm-dev-common.c | 38 ++++++++++++++++++++++++++++--------- > drivers/char/tpm/tpm-dev.h | 2 ++ > 2 files changed, 31 insertions(+), 9 deletions(-) > > diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c > index 99b5133a9d05..77e686d35384 100644 > --- a/drivers/char/tpm/tpm-dev-common.c > +++ b/drivers/char/tpm/tpm-dev-common.c > @@ -64,6 +64,7 @@ static void tpm_timeout_work(struct work_struct *work) > > mutex_lock(&priv->buffer_mutex); > priv->data_pending = 0; > + priv->partial_data = 0; What is this variable? Please refine the patch with better documentation. /Jarkko
