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Groups > linux.kernel > #1713280
| From | Ken Goldman <kgold@linux.vnet.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: Aw: Re: [tpmdd-devel] [PATCH] tpm: improve tpm_tis send() performance by ignoring burstcount |
| Date | 2017-08-16 22:00 +0200 |
| Message-ID | <ufcDT-2Ry-11@gated-at.bofh.it> (permalink) |
| References | (2 earlier) <ucicO-4h6-15@gated-at.bofh.it> <ucFM5-3O1-5@gated-at.bofh.it> <ucG5t-3Vm-43@gated-at.bofh.it> <udq8i-la-5@gated-at.bofh.it> <ufcDT-2Ry-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 8/14/2017 6:10 AM, Jarkko Sakkinen wrote: >> Nuvoton, ST Micro, and Infineon confirmed that the TPM empties a byte from >> the FIFO in under 1 usec. So, even with a static burst count, the entire >> FIFO would empty in under 10 usec. > > Does this break anything lets say in a decade time frame? If it does, I > will not even consider this. Can you give a definitive answer for that? My attempt at predicting the future ... 1 - Clock speed should get faster, not slower, so the 1 usec wait state should get shorter. 2 - TPM buffers should get larger. I'm already reading of 256 byte buffers. So there should be fewer wait states. 3 - There is a trend toward using the CRB, making the FIFO less applicable. 4 - There is a trend away from LPC connected serial port devices, printers, and PS/2 mouse and keyboard, and toward USB connected devices. I assume this will continue, making the already insignificant wait states irrelevant.
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Re: Aw: Re: [tpmdd-devel] [PATCH] tpm: improve tpm_tis send() performance by ignoring burstcount Ken Goldman <kgold@linux.vnet.ibm.com> - 2017-08-16 22:00 +0200
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