input: dynamically allocate ABS information
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From: Dmitry Torokhov on 24 May 2010 12:20 On Mon, May 24, 2010 at 06:08:05PM +0200, Daniel Mack wrote: > Hi Dmitry, > > any feelings about this approach? > Still pondering...I applied the very first patch though... Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Daniel Mack on 16 Jun 2010 04:40 Hi Dmitry, On Mon, May 24, 2010 at 09:15:28AM -0700, Dmitry Torokhov wrote: > On Mon, May 24, 2010 at 06:08:05PM +0200, Daniel Mack wrote: > > any feelings about this approach? > > > > Still pondering...I applied the very first patch though... Any news about this? I have no problem throwing away the whole patch set and use a different approach, if there is any :) And I need one, because I have a patch pending for a MIDI/Controller device which is something like a drum computer control device, and this one has more ABS information channels than currently supported by the input stack. OTOH, the current plan is to use *axis* information for the transport to the user space, but in fact, their hardware representation is a pressure-sesitive button. Same counts for potentiometers etc, which aren't axis either. So maybe I should use some different layer for such devices? MIDI legacy after all? I'm open to any suggestions :) Thanks, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Dmitry Torokhov on 14 Jul 2010 04:20 On Wed, May 19, 2010 at 07:22:37PM +0200, Daniel Mack wrote: > > /** > + * input_alloc_absinfo - allocates an input_absinfo struct > + * @dev: the input device > + * @axis: the ABS axis > + * > + * If the absinfo struct the caller asked for is already allocated, this > + * functions will not do anything but return it. > + */ > +struct input_absinfo *input_alloc_absinfo(struct input_dev *dev, int axis) > +{ > + if (!dev->absinfo[axis]) > + dev->absinfo[axis] = > + kzalloc(sizeof(struct input_absinfo), GFP_KERNEL); > + > + WARN(!dev->absinfo[axis], "%s(): kzalloc() failed?\n", __func__); > + return dev->absinfo[axis]; This causes us to allocate every absinfo structure separately and use 64 additional pointers (256 bytes on 32 bit boxes and even more on 64 bit boxes). If device uses enough axis we end up eating up most savings. I think we should simply alloctate ABS_CNT worth of absinfo first time we try to set up abs parameters and be done with it so we'll be saving space for devices not reporting absolute events. Another optionw woudl be to allow drivers specify size of absinfo array but I am not sure if it worth it. Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: ext-phil.2.carmody on 21 Jul 2010 05:30 A tiny tiny nit... From: Dmitry Torokhov [dmitry.torokhov(a)gmail.com] .... +void input_alloc_absinfo(struct input_dev *dev) +{ + if (!dev->absinfo) + dev->absinfo = kcalloc(ABS_CNT, sizeof(struct input_absinfo), + GFP_KERNEL); + + WARN(!dev->absinfo, "%s(): kzalloc() failed?\n", __func__); kcalloc failed, not kzalloc. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Artem Bityutskiy on 21 Jul 2010 07:00
On Wed, 2010-07-21 at 11:22 +0200, ext-phil.2.carmody(a)nokia.com wrote: > A tiny tiny nit... > > From: Dmitry Torokhov [dmitry.torokhov(a)gmail.com] > ... > +void input_alloc_absinfo(struct input_dev *dev) > +{ > + if (!dev->absinfo) > + dev->absinfo = kcalloc(ABS_CNT, sizeof(struct input_absinfo), > + GFP_KERNEL); > + > + WARN(!dev->absinfo, "%s(): kzalloc() failed?\n", __func__); > > kcalloc failed, not kzalloc. kmalloc and friends already print a warning with a stack dump when they fail, unless this is overrided with __GFP_NOWARN, which is not the case here. So in usually we do not print messages/warnigns when we fail to allocate. -- Best Regards, Artem Bityutskiy (Артём Битюцкий) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |