[alsa-devel] [PATCH 13/19] ASoC: Intel: mrfld: add bytes control for modules

[Vinod Koul]

On Sat, Jun 21, 2014 at 08:19:13AM +0200, Lars-Peter Clausen wrote:
> >>>>>+static const struct snd_kcontrol_new sst_algo_controls[] = {
> >>>>>+	SST_ALGO_KCONTROL_BYTES("media_loop1_out", "fir", 272, SST_MODULE_ID_FIR_24,
> >>>>>+		 SST_PATH_INDEX_MEDIA_LOOP1_OUT, 0, SST_TASK_SBA, SBA_VB_SET_FIR),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("media_loop1_out", "iir", 300, SST_MODULE_ID_IIR_24,
> >>>>>+		SST_PATH_INDEX_MEDIA_LOOP1_OUT, 0, SST_TASK_SBA, SBA_VB_SET_IIR),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("media_loop1_out", "mdrp", 286, SST_MODULE_ID_MDRP,
> >>>>>+		SST_PATH_INDEX_MEDIA_LOOP1_OUT, 0, SST_TASK_SBA, SBA_SET_MDRP),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("media_loop2_out", "fir", 272, SST_MODULE_ID_FIR_24,
> >>>>>+		SST_PATH_INDEX_MEDIA_LOOP2_OUT, 0, SST_TASK_SBA, SBA_VB_SET_FIR),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("media_loop2_out", "iir", 300, SST_MODULE_ID_IIR_24,
> >>>>>+		SST_PATH_INDEX_MEDIA_LOOP2_OUT, 0, SST_TASK_SBA, SBA_VB_SET_IIR),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("media_loop2_out", "mdrp", 286, SST_MODULE_ID_MDRP,
> >>>>>+		SST_PATH_INDEX_MEDIA_LOOP2_OUT, 0, SST_TASK_SBA, SBA_SET_MDRP),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("sprot_loop_out", "lpro", 192, SST_MODULE_ID_SPROT,
> >>>>>+		SST_PATH_INDEX_SPROT_LOOP_OUT, 0, SST_TASK_SBA, SBA_VB_LPRO),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("codec_in0", "dcr", 52, SST_MODULE_ID_FILT_DCR,
> >>>>>+		SST_PATH_INDEX_CODEC_IN0, 0, SST_TASK_SBA, SBA_VB_SET_IIR),
> >>>>>+	SST_ALGO_KCONTROL_BYTES("codec_in1", "dcr", 52, SST_MODULE_ID_FILT_DCR,
> >>>>>+		SST_PATH_INDEX_CODEC_IN1, 0, SST_TASK_SBA, SBA_VB_SET_IIR),
> >>>>
> >>>>
> >>>>You are creating a lot of global non-const variables here that are
> >>>>later modified in the put and get handlers and also elsewhere.
> >>>Sorry which ones above are modfied. Above values are information for headers of
> >>>IPCs which we send to DSPs
> >>>
> >>
> >>The SST_ALGO_CTL_VALUE() macro uses compound literals to create a
> >>global (nameless) struct. A pointer to this struct is assigned to
> >>the kcontrols private_value field. This is later read and the struct
> >>is modified.
> >Yes but not the above values as these as IPC header info which DSP needs.
> >
> 
> The SST_ALGO_KCONTROL_BYTES() macro calls SST_ALGO_KCONTROL() which
> in return calls SST_ALGO_CTL_VALUE()
Yes and 
#define SST_ALGO_CTL_VALUE(xcount, xtype, xpipe, xmod, xtask, xcmd)	\
        (struct sst_algo_control){					\
                .max = xcount + sizeof(u16), .type = xtype, .module_id = xmod,\
                .pipe_id = xpipe, .task_id = xtask, .cmd_id = xcmd,\
        }

So these values passed above are filled here and put in private_data as you
rightly noticed. But later on get/put handlers will not modify these specfic
value but other private value. Above are used _only_ for IPC headers to DSP so
we cant afford to modify them. We cna try making these values above as
consts, static

-- 
~Vinod