Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH 0/2] spi: fsi: Reduce max transfer size to 8 bytes | Date | Sat, 17 Jul 2021 13:46:15 +0000 |
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From: Eddie James > Sent: 16 July 2021 14:39 > > The security restrictions on the FSI-attached SPI controllers have > been applied universally to all controllers, so the controller can no > longer transfer more than 8 bytes for one transfer. Refactor the driver > to remove the looping and support for larger transfers, and remove the > "restricted" compatible string, as all the controllers are now > considered restricted.
Aren't there significant performance (and device wear?) penalties for doing short SPI eeprom writes?
IIRC (and I'm not getting my serial busses confused) a write request can request an aligned transfer of up to (typically) 32 bytes. At which point you need to wait for the status to indicate 'complete'.
So restricting writes to 8 bytes increases block write times by a factor of 4.
Increasing the numbers of writes by a factor or 4 may also have an effect on device wear - but that is more likely only affected by erase cycles.
David
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