Dear Stefan, In message <200901051912.25874...@denx.de> you wrote: > > > > + /* Write new configration */ > > > + out_8(&hw->regs->mode, cs->mode); > > > + > > > + /* > > > + * Allow platform reduce the interrupt load on the CPU during SPI > > > + * transfers. We do not target maximum performance, but rather allow > > > + * platform to limit SPI bus frequency and interrupt rate. > > > > That comment doesn't seem even vaguely related to the > > code it allegedly refers to ... nothing in this routine > > affects the IRQ load. > > IIRC (I didn't write the original version of this driver) then this comments > simply refers to the fact that the platform can select a maximum SPI > frequency via spi->max_speed_hz which is pretty obvious. So I'll just remove > this comment in the next version.
On PPC4xx systems we get one interrupt per transferred byte, i. e. there is a direct relation between SPI bus frequency and interrupt rate. Since this is a PPC4xx SPI driver, the comment is actually helpful to understand the operation of the driver especially in relation to the limitations of the hardware. Instead of removing the comment (which leaves the casual reader clueless) it would probably better to add a sentence explaining the one byte / one interrupt situation? Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de ...when fits of creativity run strong, more than one programmer or writer has been known to abandon the desktop for the more spacious floor. - Fred Brooks, Jr. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
