On Fri, Jan 06, 2023 at 12:07:59PM -0800, William Zhang wrote:I agree but this is more for backward compatibility as the original driver uses interrupt to work with MIPS based SoC and I do not want to change that behavior. For newer devices I added, they work in polling mode by default with the dts I supplied. IMHO it is also good to have this fallback option to use interrupt in case user is sensitive to cpu usage.
Polling mode provides better throughput in general by avoiding the
interrupt overhead as the maximum data size one interrupt can handle is
only 512 bytes.
When interrupt is not defined in the HSSPI dts node, driver switches to
polling mode for controller SPI message processing. Also add driver
banner message when the driver is loaded successfully.
This should not be something the user selects via the DT, if the polling
mode is better then the driver should just use it regardless of there
being an interrupt wired up. Generally there's some point at which the
benefits of polling become minimal (and the costs more impactful) but if
the DMA setup is as bad as it sounds then the driver should just ignore
the interrupt.
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