Re: how to detect SD card under linux

On Mon, 9 Jul 2007, jian tao wrote:

> Hi pals,
> 
> I am a new guy of linux usb driver. I met a problem with detecting SD
> card under linux2.6.11. My developing board: MPC8349 EHCI host -->
> ISP1505 (usb PHY) --->USB2227 (SMSC Flash card Reader chip). When
> linux booting, i would success to detect usb2227 see below log.
>  Then i plug in SD card, nothing could happen, it fail to find scsi
> device. I know there would be three kernel threads to polling current
> usb status. One is "hub_thread" to polling port status; one is
> "usb_stor_control_thread" to dealing with scsi cmd; another is
> "usb_stor_scan_thread" to scan scsi devie.
> 
>  Question1:
>  when i plug SD card in USB2227 card reader, which thread would
> responsible such event? i guess it must be the "usb_stor_scan_thread".

No.  None of the threads you listed is responsible.  In practice the 
detection is done by HAL, a userspace daemon.

>  Question2:
> The function sd_probe would be called when a new scsi device attached.
> What is the relationship between daemon process and this function?

Which daemon process are you talking about?  In general there is no
connection between any daemons and sd_probe.

>  Question3:
>  What may the main cause of such issue? (suppose no hardware issue)

Your question isn't clear.  Are you asking why the kernel does not 
detect the SCSI device?  But it _does_ detect the SCSI device, as you 
can see from your own log:

>  LOG:
>  Initializing USB Mass Storage driver...
>  usb 1-1: new high speed USB device using fsl-usb2-mph and address 2
>  usb 1-1: Product: Flash Card Reader
>  usb 1-1: Manufacturer: Generic
>  usb 1-1: SerialNumber: 000022272228
>  Begain run the storage_probe function
>  USB Mass Storage device detected
>  scsi1 : SCSI emulation for USB Mass Storage devices
>  usbcore: registered new driver usb-storage
>  USB Mass Storage support registered.
>  .....
>    Vendor: Generic   Model: Flash HS-CF       Rev: 3.95
>    Type:   Direct-Access                      ANSI SCSI revision: 00
>  Attached scsi removable disk sdb at scsi1, channel 0, id 0, lun 0

The last line shows that the kernel has detected a SCSI disk.

Are you asking why the SD card wasn't detected when you put in in the 
reader?  Probably because you weren't running HAL.

Alan Stern


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