[PATCH] usb: storage: add quirks for CASIO calculators

[PATCH] usb: storage: add quirks for CASIO calculators

[Thomas Touhey]

CASIO calculators using USB Mass Storage, bearing
product IDs 6102 and 6103, always report non-zero
dCSWDataResidue for requested transfer length
>4096 bytes while bCSWStatus == 0.

Information about an fx-CG50 (OS 3.11):
T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 24 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=07cf ProdID=6102 Rev= 1.00
S:  Manufacturer=CASIO MassStorage Device
S:  Product=CASIO MassStorage Device
S:  SerialNumber=0000xdPUBVUq
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms

Information about an fx-9750GIII (OS 3.71):
T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 25 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=07cf ProdID=6103 Rev= 1.00
S:  Manufacturer=CASIO MassStorage Device
S:  Product=CASIO MassStorage Device
S:  SerialNumber=000000000001
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms

Cc: stable <stable@kernel.org>
Signed-off-by: Thomas Touhey <thomas@touhey.fr>
---
 drivers/usb/storage/unusual_devs.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
index ac22fa318734..492b5f050f0b 100644
--- a/drivers/usb/storage/unusual_devs.h
+++ b/drivers/usb/storage/unusual_devs.h
@@ -1168,6 +1168,25 @@ UNUSUAL_DEV( 0x07cf, 0x1167, 0x0100, 0x0100,
 		"EX-N1 DigitalCamera",
 		USB_SC_8070, USB_PR_DEVICE, NULL, 0),
 
+/*
+ * CASIO calculators using UMS for "USB Key" mode always
+ * reports non-zero residue when the transfer length is larger
+ * than 4096 bytes.
+ *
+ * Reported by Thomas Touhey <thomas@touhey.fr>
+ * and augmented by 0v0katai <0v0katai@gmail.com>
+ */
+UNUSUAL_DEV( 0x07cf, 0x6102, 0x0100, 0x0100,
+	     "Casio",
+	     "fx-CP400",
+	     USB_SC_DEVICE, USB_PR_DEVICE, NULL,
+	     US_FL_IGNORE_RESIDUE ),
+UNUSUAL_DEV( 0x07cf, 0x6103, 0x0100, 0x0100,
+	     "Casio",
+	     "fx-CG50",
+	     USB_SC_DEVICE, USB_PR_DEVICE, NULL,
+	     US_FL_IGNORE_RESIDUE ),
+
 /* Submitted by Hartmut Wahl <hwahl@hwahl.de>*/
 UNUSUAL_DEV( 0x0839, 0x000a, 0x0001, 0x0001,
 		"Samsung",
-- 
2.56.0

Re: [PATCH] usb: storage: add quirks for CASIO calculators

[sashiko-bot]

> CASIO calculators using USB Mass Storage, bearing
> product IDs 6102 and 6103, always report non-zero
> dCSWDataResidue for requested transfer length
> >4096 bytes while bCSWStatus == 0.
> 
> Information about an fx-CG50 (OS 3.11):
> T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 24 Spd=480  MxCh= 0
> D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=07cf ProdID=6102 Rev= 1.00
> S:  Manufacturer=CASIO MassStorage Device
> S:  Product=CASIO MassStorage Device
> S:  SerialNumber=0000xdPUBVUq
> C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
> I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> [ ... ]
> E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> 
> Cc: stable <stable@kernel.org>
> Signed-off-by: Thomas Touhey <thomas@touhey.fr>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261105151348.19009-1-thomas@touhey.fr?part=1

Re: [PATCH] usb: storage: add quirks for CASIO calculators

[Alan Stern]

On Thu, Nov 05, 2026 at 04:13:48PM +0100, Thomas Touhey wrote:
> CASIO calculators using USB Mass Storage, bearing
> product IDs 6102 and 6103, always report non-zero
> dCSWDataResidue for requested transfer length
> >4096 bytes while bCSWStatus == 0.

Do the calculators' Mass Storage interface work correctly when the quirk 
is present?  In other words, is the non-zero dCSWDataResidue value 
simply wrong, or does it accurately reflect the fact that the device 
hasn't accepted anything beyond the first 4 KB of the data transfer?

If the latter is true then the quirk won't help.  Instead it would be 
necessary to set the device's max_sectors value to 8, limiting 
individual transfers to 8 * 512 = 4096 bytes.

How much storage space do these devices provide?

Alan Stern

> Information about an fx-CG50 (OS 3.11):
> T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 24 Spd=480  MxCh= 0
> D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=07cf ProdID=6102 Rev= 1.00
> S:  Manufacturer=CASIO MassStorage Device
> S:  Product=CASIO MassStorage Device
> S:  SerialNumber=0000xdPUBVUq
> C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
> I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> 
> Information about an fx-9750GIII (OS 3.71):
> T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 25 Spd=480  MxCh= 0
> D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=07cf ProdID=6103 Rev= 1.00
> S:  Manufacturer=CASIO MassStorage Device
> S:  Product=CASIO MassStorage Device
> S:  SerialNumber=000000000001
> C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
> I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> 
> Cc: stable <stable@kernel.org>
> Signed-off-by: Thomas Touhey <thomas@touhey.fr>
> ---
>  drivers/usb/storage/unusual_devs.h | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
> index ac22fa318734..492b5f050f0b 100644
> --- a/drivers/usb/storage/unusual_devs.h
> +++ b/drivers/usb/storage/unusual_devs.h
> @@ -1168,6 +1168,25 @@ UNUSUAL_DEV( 0x07cf, 0x1167, 0x0100, 0x0100,
>  		"EX-N1 DigitalCamera",
>  		USB_SC_8070, USB_PR_DEVICE, NULL, 0),
>  
> +/*
> + * CASIO calculators using UMS for "USB Key" mode always
> + * reports non-zero residue when the transfer length is larger
> + * than 4096 bytes.
> + *
> + * Reported by Thomas Touhey <thomas@touhey.fr>
> + * and augmented by 0v0katai <0v0katai@gmail.com>
> + */
> +UNUSUAL_DEV( 0x07cf, 0x6102, 0x0100, 0x0100,
> +	     "Casio",
> +	     "fx-CP400",
> +	     USB_SC_DEVICE, USB_PR_DEVICE, NULL,
> +	     US_FL_IGNORE_RESIDUE ),
> +UNUSUAL_DEV( 0x07cf, 0x6103, 0x0100, 0x0100,
> +	     "Casio",
> +	     "fx-CG50",
> +	     USB_SC_DEVICE, USB_PR_DEVICE, NULL,
> +	     US_FL_IGNORE_RESIDUE ),
> +
>  /* Submitted by Hartmut Wahl <hwahl@hwahl.de>*/
>  UNUSUAL_DEV( 0x0839, 0x000a, 0x0001, 0x0001,
>  		"Samsung",
> -- 
> 2.56.0
> 
> 

Re: [PATCH] usb: storage: add quirks for CASIO calculators

[Thomas Touhey]

Hey, thanks for your review and response!

> How much storage space do these devices provide?

Usually between 2MB to around 32MB (usually around 15-20MB on modern devices).

> Do the calculators' Mass Storage interface work correctly when the quirk
> is present?  In other words, is the non-zero dCSWDataResidue value
> simply wrong, or does it accurately reflect the fact that the device
> hasn't accepted anything beyond the first 4 KB of the data transfer?

It does, the dCSWDataResidue is wrong. We made two experiments, one on
Linux and one on Win32.

0v0katai (quoted in the commit) tested this on Win32 with the default
driver (USBSTOR), which seems to already ignore the CSW residue in
this situation. They wrote a random 1M file it, read it back, then
compared SHA256 hashes; they were identical. The writing part can be
found in the attached "test-win32-write1M.pcapng" file.

I tested this on Linux by applying the quirk using "options
usb-storage quirks=07cf:6102:r,07cf:6103:r" with modprobe, starting my
Graph 90+E (French variant of the fx-CG50) in USB Key mode, writing
the file ("test-linux-00-write4M" file), detaching, reattaching,
reading the file ("test-linux-01-read4M"), then diff-ing both the
source and the obtained file. Identical once again. :-)

Let me know if there are additional tests I should run!

Regards,
Thomas Touhey

P-S: Resending with all recipients this time, because I answered to
you only by mistake. Sorry, new to the git review process by e-mail
:-)

Le jeu. 5 nov. 2026 à 17:02, Alan Stern <stern@rowland.harvard.edu> a écrit :
>
> On Thu, Nov 05, 2026 at 04:13:48PM +0100, Thomas Touhey wrote:
> > CASIO calculators using USB Mass Storage, bearing
> > product IDs 6102 and 6103, always report non-zero
> > dCSWDataResidue for requested transfer length
> > >4096 bytes while bCSWStatus == 0.
>
> Do the calculators' Mass Storage interface work correctly when the quirk
> is present?  In other words, is the non-zero dCSWDataResidue value
> simply wrong, or does it accurately reflect the fact that the device
> hasn't accepted anything beyond the first 4 KB of the data transfer?
>
> If the latter is true then the quirk won't help.  Instead it would be
> necessary to set the device's max_sectors value to 8, limiting
> individual transfers to 8 * 512 = 4096 bytes.
>
> How much storage space do these devices provide?
>
> Alan Stern
>
> > Information about an fx-CG50 (OS 3.11):
> > T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 24 Spd=480  MxCh= 0
> > D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> > P:  Vendor=07cf ProdID=6102 Rev= 1.00
> > S:  Manufacturer=CASIO MassStorage Device
> > S:  Product=CASIO MassStorage Device
> > S:  SerialNumber=0000xdPUBVUq
> > C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
> > I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> > E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> > E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> >
> > Information about an fx-9750GIII (OS 3.71):
> > T:  Bus=03 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 25 Spd=480  MxCh= 0
> > D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> > P:  Vendor=07cf ProdID=6103 Rev= 1.00
> > S:  Manufacturer=CASIO MassStorage Device
> > S:  Product=CASIO MassStorage Device
> > S:  SerialNumber=000000000001
> > C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
> > I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> > E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> > E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> >
> > Cc: stable <stable@kernel.org>
> > Signed-off-by: Thomas Touhey <thomas@touhey.fr>
> > ---
> >  drivers/usb/storage/unusual_devs.h | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
> > index ac22fa318734..492b5f050f0b 100644
> > --- a/drivers/usb/storage/unusual_devs.h
> > +++ b/drivers/usb/storage/unusual_devs.h
> > @@ -1168,6 +1168,25 @@ UNUSUAL_DEV( 0x07cf, 0x1167, 0x0100, 0x0100,
> >               "EX-N1 DigitalCamera",
> >               USB_SC_8070, USB_PR_DEVICE, NULL, 0),
> >
> > +/*
> > + * CASIO calculators using UMS for "USB Key" mode always
> > + * reports non-zero residue when the transfer length is larger
> > + * than 4096 bytes.
> > + *
> > + * Reported by Thomas Touhey <thomas@touhey.fr>
> > + * and augmented by 0v0katai <0v0katai@gmail.com>
> > + */
> > +UNUSUAL_DEV( 0x07cf, 0x6102, 0x0100, 0x0100,
> > +          "Casio",
> > +          "fx-CP400",
> > +          USB_SC_DEVICE, USB_PR_DEVICE, NULL,
> > +          US_FL_IGNORE_RESIDUE ),
> > +UNUSUAL_DEV( 0x07cf, 0x6103, 0x0100, 0x0100,
> > +          "Casio",
> > +          "fx-CG50",
> > +          USB_SC_DEVICE, USB_PR_DEVICE, NULL,
> > +          US_FL_IGNORE_RESIDUE ),
> > +
> >  /* Submitted by Hartmut Wahl <hwahl@hwahl.de>*/
> >  UNUSUAL_DEV( 0x0839, 0x000a, 0x0001, 0x0001,
> >               "Samsung",
> > --
> > 2.56.0
> >
> >

Re: [PATCH] usb: storage: add quirks for CASIO calculators

[Alan Stern]

On Thu, Nov 05, 2026 at 07:43:07PM +0100, Thomas Touhey wrote:
> Hey, thanks for your review and response!
> 
> > How much storage space do these devices provide?
> 
> Usually between 2MB to around 32MB (usually around 15-20MB on modern devices).
> 
> > Do the calculators' Mass Storage interface work correctly when the quirk
> > is present?  In other words, is the non-zero dCSWDataResidue value
> > simply wrong, or does it accurately reflect the fact that the device
> > hasn't accepted anything beyond the first 4 KB of the data transfer?
> 
> It does, the dCSWDataResidue is wrong. We made two experiments, one on
> Linux and one on Win32.
> 
> 0v0katai (quoted in the commit) tested this on Win32 with the default
> driver (USBSTOR), which seems to already ignore the CSW residue in
> this situation. They wrote a random 1M file it, read it back, then
> compared SHA256 hashes; they were identical. The writing part can be
> found in the attached "test-win32-write1M.pcapng" file.
> 
> I tested this on Linux by applying the quirk using "options
> usb-storage quirks=07cf:6102:r,07cf:6103:r" with modprobe, starting my
> Graph 90+E (French variant of the fx-CG50) in USB Key mode, writing
> the file ("test-linux-00-write4M" file), detaching, reattaching,
> reading the file ("test-linux-01-read4M"), then diff-ing both the
> source and the obtained file. Identical once again. :-)
> 
> Let me know if there are additional tests I should run!

No, that's fine.  I just wanted to make sure you had considered this 
possibility.

As for the patch:

Acked-by: Alan Stern <stern@rowland.harvard.edu>

Alan Stern

Re: [PATCH] usb: storage: add quirks for CASIO calculators

[Artem Novak]

Tested on a Casio fx-9750GIII running OS 3.71
(USB ID 07cf:6103).

With US_FL_IGNORE_RESIDUE enabled through the usb-storage
runtime quirks parameter, 8 KiB reads and a 1 MiB
write/readback test passed. The readback was verified
using SHA-256 and cmp after disconnecting and reconnecting
the calculator.

Tested-by: Artem Novak <artem122novak@gmail.com>