> Mark Studebaker wrote: > > good question. > > you want to make the size bigger or smaller? I need it to be smaller, but a maximum size of 32 is o.k. for me. > I'll assume you are using a bit-banging (i2c-algo-bit) adatper here... Yes. > It's true, if you use the call > i2c_smbus_read_i2c_block_data(), > the size is fixed at 32. This is enforced in these functions > and in i2c_smbus_xfer_emulated(). > > You can avoid this limitation by making a direct call to > i2c_transfer(), you should be able to find some drivers in > the kernel that use i2c_transfer() > as an example. I think that is too low level, I need to call that function from user-space; I don't want to make a special driver-module for my device. > If you have a proposal on a clean way to set the size on calls to > i2c_smbus_read_i2c_block_data() > we'll be happy to discuss it with you. I have a solution that works for me. The changes I made are quite small. I changed the i2c_smbus_read_i2c_block_data function and added a length parameter. I think this is the right thing to do because only the I2C master knows how many byte to transfer. Then I pass the length in the i2c_smbus_data union in block[0] down to all driver sub-functions, as it is done in the _write_ functions. This allows me to adjust the block-size between 1..32, that's good enough for me. Of course this is a change in the API and will probably break some existing clients. I don't have any, so no problem for me ;-) I don't know if this is acceptable for a future version of the i2c driver. And there is still a max. size of 32 bytes for the transfer, but changing that would require to allocate the buffer dynamically. I think that's not worth the effort required. Groetjes, Andre > Andre Fisser wrote: > > Hi, > > > > are there plans to remove the fixed size of i2c block > reads? I use the > > I2C driver to communicate through the printer port with a kind of > > Philips dongle to a custom microprocessor circuit. The fixed block > > size is wasting bus-bandwidth which is a problem for me. > I'm planning > > to remove this limitation myself if there's nobody already > working on > > it. Maybe you guys have some advice for me how it can be best done? > > > > Best regards, > > Andre > > > > > > Andr? Fisser > > > > Imtech ICT Technical Systems > > Flight Forum 800, > > 5657 DV Eindhoven > > > > Telephone +31 (0)40 8484444 > > Fax +31 (0)40 8484440 > > Email Andre.Fisser at Imtech.nl > > www www.imtech.nl > > > > Imtech ICT is een full service ICT-dienstverlener die op een > > no-nonsense manier bijdraagt aan het succes van haar > klanten. Imtech > > ICT biedt hoogwaardige dienstverlening op het gebied van > > projectmanagement, advies, technische automatisering, > informatisering > > en communicatietechnologie, en is onderdeel van het beursgenoteerde > > Imtech. > > > > > > >
