Em Mon, 4 Mar 2013 17:20:05 -0300
Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> escreveu:
> Em Sun, 3 Mar 2013 20:40:57 +0100
> Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu:
>
> > The webcam "SpeedLink VAD Laplace" (em2765 + ov2640) uses a special algorithm
> > for i2c communication with the sensor, which is connected to a second i2c bus.
> >
> > We don't know yet how to find out which devices support/use it.
> > It's very likely used by all em25xx and em276x+ bridges.
> > Tests with other em28xx chips (em2820, em2882/em2883) show, that this
> > algorithm always succeeds there although no slave device is connected.
> >
> > The algorithm likely also works for real I2C client devices (OV2640 uses SCCB),
> > because the Windows driver seems to use it for probing Samsung and Kodak
> > sensors.
> >
> > Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
> > ---
> > drivers/media/usb/em28xx/em28xx-cards.c | 6 +-
> > drivers/media/usb/em28xx/em28xx-i2c.c | 164 +++++++++++++++++++++++++++----
> > drivers/media/usb/em28xx/em28xx.h | 7 ++
> > 3 Dateien geändert, 159 Zeilen hinzugefügt(+), 18 Zeilen entfernt(-)
> >
> > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
> > index 5a5b637..75d4aef 100644
> > --- a/drivers/media/usb/em28xx/em28xx-cards.c
> > +++ b/drivers/media/usb/em28xx/em28xx-cards.c
> > @@ -3103,7 +3103,11 @@ static int em28xx_init_dev(struct em28xx *dev, struct usb_device *udev,
> > return retval;
> > }
> > /* Configure i2c bus */
> > - if (!dev->board.is_em2800) {
> > + if (dev->board.is_em2800) {
> > + dev->i2c_algo_type = EM28XX_I2C_ALGO_EM2800;
> > + } else {
> > + dev->i2c_algo_type = EM28XX_I2C_ALGO_EM28XX;
> > +
> > retval = em28xx_write_reg(dev, EM28XX_R06_I2C_CLK, dev->board.i2c_speed);
> > if (retval < 0) {
> > em28xx_errdev("%s: em28xx_write_reg failed!"
> > diff --git a/drivers/media/usb/em28xx/em28xx-i2c.c b/drivers/media/usb/em28xx/em28xx-i2c.c
> > index 44bef43..6e86ffc 100644
> > --- a/drivers/media/usb/em28xx/em28xx-i2c.c
> > +++ b/drivers/media/usb/em28xx/em28xx-i2c.c
> > @@ -5,6 +5,7 @@
> > Markus Rechberger <mrechberger@xxxxxxxxx>
> > Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>
> > Sascha Sommer <saschasommer@xxxxxxxxxx>
> > + Copyright (C) 2013 Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
> >
> > This program is free software; you can redistribute it and/or modify
> > it under the terms of the GNU General Public License as published by
> > @@ -270,6 +271,114 @@ static int em28xx_i2c_check_for_device(struct em28xx *dev, u16 addr)
> > }
> >
> > /*
> > + * em25xx_bus_B_send_bytes
> > + * write bytes to the i2c device
> > + */
> > +static int em25xx_bus_B_send_bytes(struct em28xx *dev, u16 addr, u8 *buf,
> > + u16 len)
> > +{
> > + int ret;
> > +
> > + if (len < 1 || len > 64)
> > + return -EOPNOTSUPP;
> > + /* NOTE: limited by the USB ctrl message constraints
> > + * Zero length reads always succeed, even if no device is connected */
> > +
> > + /* Set register and write value */
> > + ret = dev->em28xx_write_regs_req(dev, 0x06, addr, buf, len);
> > + /* NOTE:
> > + * 0 byte writes always succeed, even if no device is connected. */
> > + if (ret != len) {
> > + if (ret < 0) {
> > + em28xx_warn("writing to i2c device at 0x%x failed "
> > + "(error=%i)\n", addr, ret);
> > + return ret;
> > + } else {
> > + em28xx_warn("%i bytes write to i2c device at 0x%x "
> > + "requested, but %i bytes written\n",
> > + len, addr, ret);
> > + return -EIO;
> > + }
> > + }
> > + /* Check success */
> > + ret = dev->em28xx_read_reg_req(dev, 0x08, 0x0000);
> > + /* NOTE: the only error we've seen so far is
> > + * 0x01 when the slave device is not present */
> > + if (ret == 0x00) {
> > + return len;
> > + } else if (ret > 0) {
> > + return -ENODEV;
> > + }
> > +
> > + return ret;
> > + /* NOTE: With chips which do not support this operation,
> > + * it seems to succeed ALWAYS ! (even if no device connected) */
> > +}
> > +
> > +/*
> > + * em25xx_bus_B_recv_bytes
> > + * read bytes from the i2c device
> > + */
> > +static int em25xx_bus_B_recv_bytes(struct em28xx *dev, u16 addr, u8 *buf,
> > + u16 len)
> > +{
> > + int ret;
> > +
> > + if (len < 1 || len > 64)
> > + return -EOPNOTSUPP;
> > + /* NOTE: limited by the USB ctrl message constraints
> > + * Zero length reads always succeed, even if no device is connected */
> > +
> > + /* Read value */
> > + ret = dev->em28xx_read_reg_req_len(dev, 0x06, addr, buf, len);
> > + /* NOTE:
> > + * 0 byte reads always succeed, even if no device is connected. */
> > + if (ret != len) {
> > + if (ret < 0) {
> > + em28xx_warn("reading from i2c device at 0x%x failed "
> > + "(error=%i)\n", addr, ret);
> > + return ret;
> > + } else {
> > + em28xx_warn("%i bytes requested from i2c device at "
> > + "0x%x, but %i bytes received\n",
> > + len, addr, ret);
> > + return -EIO;
> > + }
> > + }
> > + /* Check success */
> > + ret = dev->em28xx_read_reg_req(dev, 0x08, 0x0000);
> > + /* NOTE: the only error we've seen so far is
> > + * 0x01 when the slave device is not present */
> > + if (ret == 0x00) {
> > + return len;
> > + } else if (ret > 0) {
> > + return -ENODEV;
> > + }
> > +
> > + return ret;
> > + /* NOTE: With chips which do not support this operation,
> > + * it seems to succeed ALWAYS ! (even if no device connected) */
> > +}
> > +
> > +/*
> > + * em25xx_bus_B_check_for_device()
> > + * check if there is a i2c device at the supplied address
> > + */
> > +static int em25xx_bus_B_check_for_device(struct em28xx *dev, u16 addr)
> > +{
> > + u8 buf;
> > + int ret;
> > +
> > + ret = em25xx_bus_B_recv_bytes(dev, addr, &buf, 1);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return 0;
> > + /* NOTE: With chips which do not support this operation,
> > + * it seems to succeed ALWAYS ! (even if no device connected) */
> > +}
> > +
> > +/*
> > * em28xx_i2c_xfer()
> > * the main i2c transfer function
> > */
> > @@ -277,7 +386,9 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> > struct i2c_msg msgs[], int num)
> > {
> > struct em28xx *dev = i2c_adap->algo_data;
> > - int addr, rc, i, byte;
> > + int addr, i, byte;
> > + int rc = -EOPNOTSUPP;
> > + enum em28xx_i2c_algo_type algo_type = dev->i2c_algo_type;
> >
> > if (num <= 0)
> > return 0;
> > @@ -290,10 +401,13 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> > i == num - 1 ? "stop" : "nonstop",
> > addr, msgs[i].len );
> > if (!msgs[i].len) { /* no len: check only for device presence */
> > - if (dev->board.is_em2800)
> > - rc = em2800_i2c_check_for_device(dev, addr);
> > - else
> > + if (algo_type == EM28XX_I2C_ALGO_EM28XX) {
> > rc = em28xx_i2c_check_for_device(dev, addr);
> > + } else if (algo_type == EM28XX_I2C_ALGO_EM2800) {
> > + rc = em2800_i2c_check_for_device(dev, addr);
> > + } else if (algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B) {
> > + rc = em25xx_bus_B_check_for_device(dev, addr);
> > + }
>
> That seems too messy.
>
> IMO, the best is to create 3 different em28xx_i2c_xfer() routines:
> one for em2800, one for "standard" I2c protocol, and another one for
> this em25xx one. Then, all you need to do is to embed
> static struct i2c_algorithm into struct em28xx and fill
> em28xx_algo.master_transfer to point to the correct xfer.
>
> That makes the code more readable and remove a little faster by removing
> the unneeded ifs from the code.
>
> > if (rc == -ENODEV) {
> > if (i2c_debug)
> > printk(" no device\n");
> > @@ -301,14 +415,19 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> > }
> > } else if (msgs[i].flags & I2C_M_RD) {
> > /* read bytes */
> > - if (dev->board.is_em2800)
> > - rc = em2800_i2c_recv_bytes(dev, addr,
> > + if (algo_type == EM28XX_I2C_ALGO_EM28XX) {
> > + rc = em28xx_i2c_recv_bytes(dev, addr,
> > msgs[i].buf,
> > msgs[i].len);
> > - else
> > - rc = em28xx_i2c_recv_bytes(dev, addr,
> > + } else if (algo_type == EM28XX_I2C_ALGO_EM2800) {
> > + rc = em2800_i2c_recv_bytes(dev, addr,
> > msgs[i].buf,
> > msgs[i].len);
> > + } else if (algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B) {
> > + rc = em25xx_bus_B_recv_bytes(dev, addr,
> > + msgs[i].buf,
> > + msgs[i].len);
> > + }
> > if (i2c_debug) {
> > for (byte = 0; byte < msgs[i].len; byte++)
> > printk(" %02x", msgs[i].buf[byte]);
> > @@ -319,15 +438,20 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> > for (byte = 0; byte < msgs[i].len; byte++)
> > printk(" %02x", msgs[i].buf[byte]);
> > }
> > - if (dev->board.is_em2800)
> > - rc = em2800_i2c_send_bytes(dev, addr,
> > - msgs[i].buf,
> > - msgs[i].len);
> > - else
> > + if (algo_type == EM28XX_I2C_ALGO_EM28XX) {
> > rc = em28xx_i2c_send_bytes(dev, addr,
> > msgs[i].buf,
> > msgs[i].len,
> > i == num - 1);
> > + } else if (algo_type == EM28XX_I2C_ALGO_EM2800) {
> > + rc = em2800_i2c_send_bytes(dev, addr,
> > + msgs[i].buf,
> > + msgs[i].len);
> > + } else if (algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B) {
> > + rc = em25xx_bus_B_send_bytes(dev, addr,
> > + msgs[i].buf,
> > + msgs[i].len);
> > + }
> > }
> > if (rc < 0) {
> > if (i2c_debug)
> > @@ -589,10 +713,16 @@ error:
> > static u32 functionality(struct i2c_adapter *adap)
> > {
> > struct em28xx *dev = adap->algo_data;
> > - u32 func_flags = I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> > - if (dev->board.is_em2800)
> > - func_flags &= ~I2C_FUNC_SMBUS_WRITE_BLOCK_DATA;
> > - return func_flags;
> > +
> > + if ((dev->i2c_algo_type == EM28XX_I2C_ALGO_EM28XX) ||
> > + (dev->i2c_algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B)) {
> > + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> > + } else if (dev->i2c_algo_type == EM28XX_I2C_ALGO_EM2800) {
> > + return (I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL) &
> > + ~I2C_FUNC_SMBUS_WRITE_BLOCK_DATA;
> > + }
> > +
> > + return 0; /* BUG */
>
> Please create a separate I2C register logic for bus B. It was a mistake
> to reuse the existing I2C bus for logic for both buses (ok, actually,
> no device currently uses 2 buses, as they simply don't read eeproms on
> 2 bus devices).
>
> Btw, cx231xx has a similar issue: it has 3 buses. See how it was solved there:
>
> drivers/media/usb/cx231xx/cx231xx-core.c: cx231xx_i2c_register(&dev->i2c_bus[0]);
> drivers/media/usb/cx231xx/cx231xx-core.c: cx231xx_i2c_register(&dev->i2c_bus[1]);
> drivers/media/usb/cx231xx/cx231xx-core.c: cx231xx_i2c_register(&dev->i2c_bus[2]);
>
> Of course, the em28xx-cards will need to tell on what bus the tuner and
> demods are. The em28xx I2C logic will also need to write to EM28XX_R06_I2C_CLK
> if the bus is different - the windows driver is just stupid: it just precedes all
> I2C writes by a write at reg 0x06 - we can certainly do better than that ;).
>
> If you're in doubt on how to do it, I can seek for some time to address it
> properly.
FYI, The other patches in this series are OK. I'm tagging them as
changes_requested just because they depend on this one.
Regards,
Mauro
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
