From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Herbrechtsmeier Dr.-Ing. , Stefan" Subject: Execute spi transfers inside FIQ (NMI) or panic Date: Tue, 25 Feb 2020 14:27:27 +0100 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Return-path: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Hi, would it be acceptable to add an additional function to the struct spi_controller which handle a transfer inside a NMI context or a panic? The new function will transfer data via register polling without any lock. I must execute an SPI transfer inside a fast interrupt request (FIQ) handler or a panic. The FIQ is handled as a non-maskable interrupt (NMI). Both the panic and the NMI doesn't support any interrupts. The background of the request is a non-volatile SPI memory with cached date in system memory. The cache must be synchronized back to the SPI memory after a power failure or panic. Regards   Stefan Herbrechtsmeier **