| Message ID | 20110407133717.GA3923@sortiz-mobl (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Thu, Apr 07, 2011 at 03:40:23PM +0200, Samuel Ortiz wrote: > Hi Felipe, > > On Wed, Apr 06, 2011 at 09:59:02PM +0300, Felipe Balbi wrote: > > Hi, > > > > On Wed, Apr 06, 2011 at 08:47:34PM +0200, Samuel Ortiz wrote: > > > > > > What is a "MFD cell pointer" and why is it needed in struct device? > > > > > An MFD cell is an MFD instantiated device. > > > > > MFD (Multi Function Device) drivers instantiate platform devices. Those > > > > > devices drivers sometimes need a platform data pointer, sometimes an MFD > > > > > specific pointer, and sometimes both. Also, some of those drivers have been > > > > > implemented as MFD sub drivers, while others know nothing about MFD and just > > > > > expect a plain platform_data pointer. > > > > > > > > That sounds like a bug in those drivers, why not fix them to properly > > > > pass in the correct pointer? > > > Because they're drivers for generic IPs, not MFD ones. By forcing them to use > > > MFD specific structure and APIs, we make it more difficult for platform code > > > to instantiate them. > > > > I agree. What I do on those cases is to have a simple platform_device > > for the core IP driver and use platform_device_id tables to do runtime > > checks of the small differences. If one platform X doesn't use a > > platform_bus, it uses e.g. PCI, then you make a PCI "bridge" which > > allocates a platform_device with the correct name and adds that to the > > driver model. > I see, thanks. > Below is a patch for the Xilinx SPI example. Although this would fix the > issue, we'd still have to do that on device per device basis. I had a similar > solution where MFD drivers would set a flag for sub drivers that don't need > any of the MFD bits. In that case the MFD core code would just forward the > platform data, instead of embedding it through an MFD cell. platform_data is already a fiddly bit where you don't know what structure type platform_data points at; it is implicitly known and easy to get wrong. This solution makes me *very* nervous because it would become even easier to get a mismatch on the platform_data pointer type. g. > > Cheers, > Samuel. > > --- > drivers/mfd/timberdale.c | 8 ++++---- > drivers/spi/xilinx_spi.c | 19 ++++++++++++++++++- > include/linux/mfd/core.h | 3 +++ > 3 files changed, 25 insertions(+), 5 deletions(-) > > diff --git a/drivers/mfd/timberdale.c b/drivers/mfd/timberdale.c > index 94c6c8a..c9220ce 100644 > --- a/drivers/mfd/timberdale.c > +++ b/drivers/mfd/timberdale.c > @@ -416,7 +416,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg0[] = { > .mfd_data = &timberdale_radio_platform_data, > }, > { > - .name = "xilinx_spi", > + .name = "mfd_xilinx_spi", > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > .resources = timberdale_spi_resources, > .mfd_data = &timberdale_xspi_platform_data, > @@ -476,7 +476,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg1[] = { > .mfd_data = &timberdale_radio_platform_data, > }, > { > - .name = "xilinx_spi", > + .name = "mfd_xilinx_spi", > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > .resources = timberdale_spi_resources, > .mfd_data = &timberdale_xspi_platform_data, > @@ -526,7 +526,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg2[] = { > .mfd_data = &timberdale_radio_platform_data, > }, > { > - .name = "xilinx_spi", > + .name = "mfd_xilinx_spi", > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > .resources = timberdale_spi_resources, > .mfd_data = &timberdale_xspi_platform_data, > @@ -570,7 +570,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg3[] = { > .mfd_data = &timberdale_radio_platform_data, > }, > { > - .name = "xilinx_spi", > + .name = "mfd_xilinx_spi", > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > .resources = timberdale_spi_resources, > .mfd_data = &timberdale_xspi_platform_data, > diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c > index c69c6f2..3287b84 100644 > --- a/drivers/spi/xilinx_spi.c > +++ b/drivers/spi/xilinx_spi.c > @@ -471,7 +471,11 @@ static int __devinit xilinx_spi_probe(struct platform_device *dev) > struct spi_master *master; > u8 i; > > - pdata = mfd_get_data(dev); > + if (platform_get_device_id(dev) && > + platform_get_device_id(dev)->driver_data & MFD_PLATFORM_DEVICE) > + pdata = mfd_get_data(dev); > + else > + pdata = dev->dev.platform_data; > if (pdata) { > num_cs = pdata->num_chipselect; > little_endian = pdata->little_endian; > @@ -530,6 +534,18 @@ static int __devexit xilinx_spi_remove(struct platform_device *dev) > /* work with hotplug and coldplug */ > MODULE_ALIAS("platform:" XILINX_SPI_NAME); > > +static const struct platform_device_id xilinx_spi_id_table[] = { > + { > + .name = XILINX_SPI_NAME, > + }, > + { > + .name = "mfd_xilinx_spi", > + .driver_data = MFD_PLATFORM_DEVICE, > + }, > + { }, /* Terminating Entry */ > +}; > +MODULE_DEVICE_TABLE(platform, xilinx_spi_id_table); > + > static struct platform_driver xilinx_spi_driver = { > .probe = xilinx_spi_probe, > .remove = __devexit_p(xilinx_spi_remove), > @@ -538,6 +554,7 @@ static struct platform_driver xilinx_spi_driver = { > .owner = THIS_MODULE, > .of_match_table = xilinx_spi_of_match, > }, > + .id_table = xilinx_spi_id_table, > }; > > static int __init xilinx_spi_pltfm_init(void) > diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h > index ad1b19a..13f31f4 100644 > --- a/include/linux/mfd/core.h > +++ b/include/linux/mfd/core.h > @@ -89,6 +89,9 @@ static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev) > return pdev->dev.platform_data; > } > > +/* */ > +#define MFD_PLATFORM_DEVICE BIT(0) > + > /* > * Given a platform device that's been created by mfd_add_devices(), fetch > * the .mfd_data entry from the mfd_cell that created it. > > > -- > Intel Open Source Technology Centre > http://oss.intel.com/ ------------------------------------------------------------------------------ Xperia(TM) PLAY It's a major breakthrough. An authentic gaming smartphone on the nation's most reliable network. And it wants your games. http://p.sf.net/sfu/verizon-sfdev
On Thu, Apr 07, 2011 at 07:35:15AM -0700, Grant Likely wrote: > > Below is a patch for the Xilinx SPI example. Although this would fix the > > issue, we'd still have to do that on device per device basis. I had a similar > > solution where MFD drivers would set a flag for sub drivers that don't need > > any of the MFD bits. In that case the MFD core code would just forward the > > platform data, instead of embedding it through an MFD cell. > > platform_data is already a fiddly bit where you don't know what > structure type platform_data points at; it is implicitly known and > easy to get wrong. This solution makes me *very* nervous > because it would become even easier to get a mismatch on the > platform_data pointer type. How would that be more error prone than say a board file instantiating a platform device after having set the platform_data pointer to point to an implicitely know structure reference ? Cheers, Samuel. P.S.: Would you be ok with something like the patch below ? > > --- > > drivers/mfd/timberdale.c | 8 ++++---- > > drivers/spi/xilinx_spi.c | 19 ++++++++++++++++++- > > include/linux/mfd/core.h | 3 +++ > > 3 files changed, 25 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/mfd/timberdale.c b/drivers/mfd/timberdale.c > > index 94c6c8a..c9220ce 100644 > > --- a/drivers/mfd/timberdale.c > > +++ b/drivers/mfd/timberdale.c > > @@ -416,7 +416,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg0[] = { > > .mfd_data = &timberdale_radio_platform_data, > > }, > > { > > - .name = "xilinx_spi", > > + .name = "mfd_xilinx_spi", > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > .resources = timberdale_spi_resources, > > .mfd_data = &timberdale_xspi_platform_data, > > @@ -476,7 +476,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg1[] = { > > .mfd_data = &timberdale_radio_platform_data, > > }, > > { > > - .name = "xilinx_spi", > > + .name = "mfd_xilinx_spi", > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > .resources = timberdale_spi_resources, > > .mfd_data = &timberdale_xspi_platform_data, > > @@ -526,7 +526,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg2[] = { > > .mfd_data = &timberdale_radio_platform_data, > > }, > > { > > - .name = "xilinx_spi", > > + .name = "mfd_xilinx_spi", > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > .resources = timberdale_spi_resources, > > .mfd_data = &timberdale_xspi_platform_data, > > @@ -570,7 +570,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg3[] = { > > .mfd_data = &timberdale_radio_platform_data, > > }, > > { > > - .name = "xilinx_spi", > > + .name = "mfd_xilinx_spi", > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > .resources = timberdale_spi_resources, > > .mfd_data = &timberdale_xspi_platform_data, > > diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c > > index c69c6f2..3287b84 100644 > > --- a/drivers/spi/xilinx_spi.c > > +++ b/drivers/spi/xilinx_spi.c > > @@ -471,7 +471,11 @@ static int __devinit xilinx_spi_probe(struct platform_device *dev) > > struct spi_master *master; > > u8 i; > > > > - pdata = mfd_get_data(dev); > > + if (platform_get_device_id(dev) && > > + platform_get_device_id(dev)->driver_data & MFD_PLATFORM_DEVICE) > > + pdata = mfd_get_data(dev); > > + else > > + pdata = dev->dev.platform_data; > > if (pdata) { > > num_cs = pdata->num_chipselect; > > little_endian = pdata->little_endian; > > @@ -530,6 +534,18 @@ static int __devexit xilinx_spi_remove(struct platform_device *dev) > > /* work with hotplug and coldplug */ > > MODULE_ALIAS("platform:" XILINX_SPI_NAME); > > > > +static const struct platform_device_id xilinx_spi_id_table[] = { > > + { > > + .name = XILINX_SPI_NAME, > > + }, > > + { > > + .name = "mfd_xilinx_spi", > > + .driver_data = MFD_PLATFORM_DEVICE, > > + }, > > + { }, /* Terminating Entry */ > > +}; > > +MODULE_DEVICE_TABLE(platform, xilinx_spi_id_table); > > + > > static struct platform_driver xilinx_spi_driver = { > > .probe = xilinx_spi_probe, > > .remove = __devexit_p(xilinx_spi_remove), > > @@ -538,6 +554,7 @@ static struct platform_driver xilinx_spi_driver = { > > .owner = THIS_MODULE, > > .of_match_table = xilinx_spi_of_match, > > }, > > + .id_table = xilinx_spi_id_table, > > }; > > > > static int __init xilinx_spi_pltfm_init(void) > > diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h > > index ad1b19a..13f31f4 100644 > > --- a/include/linux/mfd/core.h > > +++ b/include/linux/mfd/core.h > > @@ -89,6 +89,9 @@ static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev) > > return pdev->dev.platform_data; > > } > > > > +/* */ > > +#define MFD_PLATFORM_DEVICE BIT(0) > > + > > /* > > * Given a platform device that's been created by mfd_add_devices(), fetch > > * the .mfd_data entry from the mfd_cell that created it. > > > > > > -- > > Intel Open Source Technology Centre > > http://oss.intel.com/
On Thu, Apr 07, 2011 at 05:03:23PM +0200, Samuel Ortiz wrote: > On Thu, Apr 07, 2011 at 07:35:15AM -0700, Grant Likely wrote: > > > Below is a patch for the Xilinx SPI example. Although this would fix the > > > issue, we'd still have to do that on device per device basis. I had a similar > > > solution where MFD drivers would set a flag for sub drivers that don't need > > > any of the MFD bits. In that case the MFD core code would just forward the > > > platform data, instead of embedding it through an MFD cell. > > > > platform_data is already a fiddly bit where you don't know what > > structure type platform_data points at; it is implicitly known and > > easy to get wrong. This solution makes me *very* nervous > > because it would become even easier to get a mismatch on the > > platform_data pointer type. > How would that be more error prone than say a board file instantiating a > platform device after having set the platform_data pointer to point to an > implicitely know structure reference ? Yes, platform_data is already troublesome, but at least current convention is a 1:1 relationship between driver and platform_data type. I still hate it and want something better, but it is what we have. The problem with what having a different platform_data pointer depending on the instantiation means that it adds yet another level of decision that needs to be made and is very easy to get wrong. So, yes, platform_data is bad. I don't want to see it get any worse. > > Cheers, > Samuel. > > P.S.: Would you be ok with something like the patch below ? Not really because it requires the driver to make the correct decision about the platform_data type depending on the driver name. It is easy to get wrong and the compiler cannot help you catch it. I've talked with Greg, and adding the mfd_cell pointer to platform_device will be okay in the short term. In the long term I'm looking at creating a better way of attaching type-safe data to devices that will pretty much eliminate this issue. > > > > --- > > > drivers/mfd/timberdale.c | 8 ++++---- > > > drivers/spi/xilinx_spi.c | 19 ++++++++++++++++++- > > > include/linux/mfd/core.h | 3 +++ > > > 3 files changed, 25 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/mfd/timberdale.c b/drivers/mfd/timberdale.c > > > index 94c6c8a..c9220ce 100644 > > > --- a/drivers/mfd/timberdale.c > > > +++ b/drivers/mfd/timberdale.c > > > @@ -416,7 +416,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg0[] = { > > > .mfd_data = &timberdale_radio_platform_data, > > > }, > > > { > > > - .name = "xilinx_spi", > > > + .name = "mfd_xilinx_spi", > > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > > .resources = timberdale_spi_resources, > > > .mfd_data = &timberdale_xspi_platform_data, > > > @@ -476,7 +476,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg1[] = { > > > .mfd_data = &timberdale_radio_platform_data, > > > }, > > > { > > > - .name = "xilinx_spi", > > > + .name = "mfd_xilinx_spi", > > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > > .resources = timberdale_spi_resources, > > > .mfd_data = &timberdale_xspi_platform_data, > > > @@ -526,7 +526,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg2[] = { > > > .mfd_data = &timberdale_radio_platform_data, > > > }, > > > { > > > - .name = "xilinx_spi", > > > + .name = "mfd_xilinx_spi", > > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > > .resources = timberdale_spi_resources, > > > .mfd_data = &timberdale_xspi_platform_data, > > > @@ -570,7 +570,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg3[] = { > > > .mfd_data = &timberdale_radio_platform_data, > > > }, > > > { > > > - .name = "xilinx_spi", > > > + .name = "mfd_xilinx_spi", > > > .num_resources = ARRAY_SIZE(timberdale_spi_resources), > > > .resources = timberdale_spi_resources, > > > .mfd_data = &timberdale_xspi_platform_data, > > > diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c > > > index c69c6f2..3287b84 100644 > > > --- a/drivers/spi/xilinx_spi.c > > > +++ b/drivers/spi/xilinx_spi.c > > > @@ -471,7 +471,11 @@ static int __devinit xilinx_spi_probe(struct platform_device *dev) > > > struct spi_master *master; > > > u8 i; > > > > > > - pdata = mfd_get_data(dev); > > > + if (platform_get_device_id(dev) && > > > + platform_get_device_id(dev)->driver_data & MFD_PLATFORM_DEVICE) > > > + pdata = mfd_get_data(dev); > > > + else > > > + pdata = dev->dev.platform_data; > > > if (pdata) { > > > num_cs = pdata->num_chipselect; > > > little_endian = pdata->little_endian; > > > @@ -530,6 +534,18 @@ static int __devexit xilinx_spi_remove(struct platform_device *dev) > > > /* work with hotplug and coldplug */ > > > MODULE_ALIAS("platform:" XILINX_SPI_NAME); > > > > > > +static const struct platform_device_id xilinx_spi_id_table[] = { > > > + { > > > + .name = XILINX_SPI_NAME, > > > + }, > > > + { > > > + .name = "mfd_xilinx_spi", > > > + .driver_data = MFD_PLATFORM_DEVICE, > > > + }, > > > + { }, /* Terminating Entry */ > > > +}; > > > +MODULE_DEVICE_TABLE(platform, xilinx_spi_id_table); > > > + > > > static struct platform_driver xilinx_spi_driver = { > > > .probe = xilinx_spi_probe, > > > .remove = __devexit_p(xilinx_spi_remove), > > > @@ -538,6 +554,7 @@ static struct platform_driver xilinx_spi_driver = { > > > .owner = THIS_MODULE, > > > .of_match_table = xilinx_spi_of_match, > > > }, > > > + .id_table = xilinx_spi_id_table, > > > }; > > > > > > static int __init xilinx_spi_pltfm_init(void) > > > diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h > > > index ad1b19a..13f31f4 100644 > > > --- a/include/linux/mfd/core.h > > > +++ b/include/linux/mfd/core.h > > > @@ -89,6 +89,9 @@ static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev) > > > return pdev->dev.platform_data; > > > } > > > > > > +/* */ > > > +#define MFD_PLATFORM_DEVICE BIT(0) > > > + > > > /* > > > * Given a platform device that's been created by mfd_add_devices(), fetch > > > * the .mfd_data entry from the mfd_cell that created it. > > > > > > > > > -- > > > Intel Open Source Technology Centre > > > http://oss.intel.com/ > > -- > Intel Open Source Technology Centre > http://oss.intel.com/ ------------------------------------------------------------------------------ Xperia(TM) PLAY It's a major breakthrough. An authentic gaming smartphone on the nation's most reliable network. And it wants your games. http://p.sf.net/sfu/verizon-sfdev
diff --git a/drivers/mfd/timberdale.c b/drivers/mfd/timberdale.c index 94c6c8a..c9220ce 100644 --- a/drivers/mfd/timberdale.c +++ b/drivers/mfd/timberdale.c @@ -416,7 +416,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg0[] = { .mfd_data = &timberdale_radio_platform_data, }, { - .name = "xilinx_spi", + .name = "mfd_xilinx_spi", .num_resources = ARRAY_SIZE(timberdale_spi_resources), .resources = timberdale_spi_resources, .mfd_data = &timberdale_xspi_platform_data, @@ -476,7 +476,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg1[] = { .mfd_data = &timberdale_radio_platform_data, }, { - .name = "xilinx_spi", + .name = "mfd_xilinx_spi", .num_resources = ARRAY_SIZE(timberdale_spi_resources), .resources = timberdale_spi_resources, .mfd_data = &timberdale_xspi_platform_data, @@ -526,7 +526,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg2[] = { .mfd_data = &timberdale_radio_platform_data, }, { - .name = "xilinx_spi", + .name = "mfd_xilinx_spi", .num_resources = ARRAY_SIZE(timberdale_spi_resources), .resources = timberdale_spi_resources, .mfd_data = &timberdale_xspi_platform_data, @@ -570,7 +570,7 @@ static __devinitdata struct mfd_cell timberdale_cells_bar0_cfg3[] = { .mfd_data = &timberdale_radio_platform_data, }, { - .name = "xilinx_spi", + .name = "mfd_xilinx_spi", .num_resources = ARRAY_SIZE(timberdale_spi_resources), .resources = timberdale_spi_resources, .mfd_data = &timberdale_xspi_platform_data, diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c index c69c6f2..3287b84 100644 --- a/drivers/spi/xilinx_spi.c +++ b/drivers/spi/xilinx_spi.c @@ -471,7 +471,11 @@ static int __devinit xilinx_spi_probe(struct platform_device *dev) struct spi_master *master; u8 i; - pdata = mfd_get_data(dev); + if (platform_get_device_id(dev) && + platform_get_device_id(dev)->driver_data & MFD_PLATFORM_DEVICE) + pdata = mfd_get_data(dev); + else + pdata = dev->dev.platform_data; if (pdata) { num_cs = pdata->num_chipselect; little_endian = pdata->little_endian; @@ -530,6 +534,18 @@ static int __devexit xilinx_spi_remove(struct platform_device *dev) /* work with hotplug and coldplug */ MODULE_ALIAS("platform:" XILINX_SPI_NAME); +static const struct platform_device_id xilinx_spi_id_table[] = { + { + .name = XILINX_SPI_NAME, + }, + { + .name = "mfd_xilinx_spi", + .driver_data = MFD_PLATFORM_DEVICE, + }, + { }, /* Terminating Entry */ +}; +MODULE_DEVICE_TABLE(platform, xilinx_spi_id_table); + static struct platform_driver xilinx_spi_driver = { .probe = xilinx_spi_probe, .remove = __devexit_p(xilinx_spi_remove), @@ -538,6 +554,7 @@ static struct platform_driver xilinx_spi_driver = { .owner = THIS_MODULE, .of_match_table = xilinx_spi_of_match, }, + .id_table = xilinx_spi_id_table, }; static int __init xilinx_spi_pltfm_init(void) diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h index ad1b19a..13f31f4 100644 --- a/include/linux/mfd/core.h +++ b/include/linux/mfd/core.h @@ -89,6 +89,9 @@ static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev) return pdev->dev.platform_data; } +/* */ +#define MFD_PLATFORM_DEVICE BIT(0) + /* * Given a platform device that's been created by mfd_add_devices(), fetch * the .mfd_data entry from the mfd_cell that created it.