Hi Simon, > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Simon Glass > Sent: Saturday, April 09, 2016 3:13 AM > To: Qianyu Gong <[email protected]> > Cc: [email protected]; Mingkai Hu <[email protected]>; Yao Yuan > <[email protected]>; [email protected] > Subject: Re: A problem about 'sf probe' using DM_SPI > > Hi Qianyu, > > On 25 March 2016 at 03:34, Qianyu Gong <[email protected]> wrote: > > Hi Simon, > > > > > > > > I think I’m not very clear with this code in common/cmd_sf.c: > > > > “ > > > > # ifdef CONFIG_DM_SPI_FLASH > > > > /* Remove the old device, otherwise probe will just be a nop */ > > > > ret = spi_find_bus_and_cs(bus, cs, &bus_dev, &new); > > > > if (!ret) { > > > > device_remove(new); > > > > device_unbind(new); > > > > } > > > > ” > > > > I may understand the remove but why need to unbind the device? > > This is because otherwise 'sf probe' would be a nop if the device > already existed. The spi_flash_probe_bus_cs() call will simply return > the existing device. If something has changed on the bus, it would be > ignored. > > > > > The unbind would cause a series of free operations on the device list, > > correct? > > Yes > > > > > Then if I probe a flash twice, at the second time the driver model will > > create > > > > a new flash named ‘spi_flash@xx:xx’ using default settings because it > > doesn’t > > > > find such a device in the device list and never probes it from the board’s > > fdt again. > > Yes. > > > > > => dm tree > > > > Class Probed Name > > > > ---------------------------------------- > > > > root [ + ] root_driver > > > > simple_bus [ + ] `-- soc > > > > spi [ + ] |-- dspi@2100000 > > > > spi_flash [ ] | |-- n25q128a > > > > spi_flash [ + ] | |-- spi_flash@1:1 > > > > spi_flash [ + ] | `-- spi_flash@1:2 > > > > Fortunately the default SPI mode set by U-Boot is SPI_MODE_3 so it doesn’t > > cause > > > > issues on our boards. But if an SPI flash which only supports SPI_MODE_0 is > > used, > > > > I think it wouldn’t work properly from the second probe. > > > > Sorry if there is something wrong with my understandings. > > Just because I found my flash’s name was changed to spi-flash@xx:xx in dm > > tree > > after several probes, I began to read something about driver model.J > > Yes I think removing the unbind would be OK, except that we need a way > to show the messages at the end of spi_flash_scan(). > > Probably these messages should move out of the uclass and into a > separate call. We could add a function like spi_flash_show(struct > udevice *dev) and call it from do_spi_flash_probe() and perhaps > saveenv(). > > Regards, > Simon
Thanks for your explanation. So you mean the flash messages? Seems that removing the unbind won't affect reading ID from a real flash. But would the unbind be needed if the dts node is modified at runtime?(I'm not sure if it is necessary) Regards, Qianyu _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
