On 03/29/2017 06:38 PM, Ludovic BARRE wrote: > > > On 03/29/2017 03:57 PM, Marek Vasut wrote: >> On 03/29/2017 03:35 PM, Ludovic BARRE wrote: >> >> [...] >> >>>>>>> + writel_relaxed(CR_PRESC(presc) | CR_FTHRES(3) | CR_TCEN | >>>>>>> CR_SSHIFT >>>>>>> + | CR_EN, qspi->io_base + QUADSPI_CR); >>>>>>> + >>>>>>> + /* a minimum fsize must be set to sent the command id */ >>>>>>> + flash->fsize = 25; >>>>>> I don't understand why this is needed and the comment doesn't make >>>>>> sense. Please fix. >>>>> fsize field defines the size of external memory. >>>> What external memory ? Unclear >>> oops, fsize field defined the size of "flash memory" in stm32 qspi >>> controller. >> Errr, now I am totally lost :) Is that some internal SPI NOR ? Shouldn't >> the size be coming from DT or something ? >> >>> Number of bytes in Flash memory = 2 ^[FSIZE+1]. >>> To sent a nor cmd this field must be set (hardware issue), >>> but before "spi_nor_scan" the size of flash nor is not know. >>> So I set a temporary value (workaround). >> Is it needed before the scan ? > yes it's needed before scan (fix a "stm32 qspi controller" issue) > > sorry, I try to reformulate: > > The nor flash (external component like micron n25q128a13 > or spansion s25fl512s ...) is connected to stm32 by classic > spi-nor interface cs, clock and 1/2/4 IO lines. > > the stm32 microprocessor has a dedicated controller to > manage spi-nor interface, it's stm32 qspi. > > In stm32 qspi controller there is a register with fsize field > which define the size of nor flash (n25q128a13 or s25fl512s...). > > fsize can't be null, else the stm32 qspi controller doesn't send > spi-nor command. it's "stm32 qspi controller" issue. > > Before the "spi_nor_scan" the size of nor flash (n25q128a13 > or s25fl512s...) is not know. So we set a temporary value just > to discover the nor flash with "spi_nor_scan". After we can > set the right value (mtd->size) in fsize. I see, now it makes sense. Such a beefy comment would be nice :) -- Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
