On Fri, Dec 08, 2017 at 07:46:52PM +0100, Alexander Steffen wrote: > According to TIS/PTP the dataAvail flag and the Expect flag in the STS > register contain valid values if and only if the stsValid flag in the same > register is set. Currently, the code first waits for the stsValid flag to What is "the code"? > be set and then looks at the other flags. This causes the STS register to > be read twice, so that the stsValid flag might not be set anymore when the > other flags are evaluated. I can understand from this paragraph is that flags should be set atomically, which makes sense. > Other parts of the code already check both flags in a single operation > within wait_for_tpm_stat. But the current implementation can only check for > flags being set to 1, not 0. Therefore, add a parameter to > wait_for_tpm_stat that allows to specify the expected value in addition to > the selected flags and adapt all callers accordingly. What are the "other parts of the code"? > In addition, this now checks the dataAvail and Expect flags multiple times What is "this"? > within the specified timeout, so those flags no longer need to have the > expected value right away. This is important for example when sending large > amounts of data to the TPM, when the TPM might not process its I/O buffer > fast enough for the flags to be set correctly when they are checked for the > first time. About the code change itself. Is there any play where you would not bitwise or TPM_STS_VALID in mask and value parameters? I guess I understand what you are doing but the commit message is complete nonsense. /Jarkko
