On 10-09-20, 08:53, Pierre-Louis Bossart wrote: > > > On 9/10/20 1:22 AM, Vinod Koul wrote: > > On 09-09-20, 08:48, Pierre-Louis Bossart wrote: > > > > > > > > > > + * 25 0 (Reserved) > > > > > > > + * 24:22 Function Number [2:0] > > > > > > > + * 21 Entity[6] > > > > > > > + * 20:19 Control Selector[5:4] > > > > > > > + * 18 0 (Reserved) > > > > > > > + * 17:15 Control Number[5:3] > > > > > > > + * 14 Next > > > > > > > + * 13 MBQ > > > > > > > + * 12:7 Entity[5:0] > > > > > > > + * 6:3 Control Selector[3:0] > > > > > > > + * 2:0 Control Number[2:0] > > > > > > > + */ > > > > > > > + > > > > > > > +#define SDW_SDCA_CTL(fun, ent, ctl, ch) \ > > > > > > > + (BIT(30) | \ > > > > > > > > > > > > Programmatically this is fine, but then since we are defining for the > > > > > > description above, IMO it would actually make sense for this to be defined > > > > > > as FIELD_PREP: > > > > > > > > > > > > FIELD_PREP(GENMASK(30, 26), 1) > > > > > > > > > > > > or better > > > > > > > > > > > > u32_encode_bits(GENMASK(30, 26), 1) > > > > > > > > > > > > > + FIELD_PREP(GENMASK(24, 22), FIELD_GET(GENMASK(2, 0), (fun))) | \ > > > > > > > > > > > > Why not use u32_encode_bits(GENMASK(24, 22), (fun)) instead for this and > > > > > > below? > > > > > > > > > > Because your comment for the v1 review was to use FIELD_PREP/FIELD_GET, and > > > > > your other patches for bitfield access only use FIELD_PREP/FIELD_GET. > > > > > > > > yes and looking at this, I feel u32_encode_bits(GENMASK(24, 22), (fun)) > > > > would look better than FIELD_PREP(GENMASK(24, 22), FIELD_GET(GENMASK(2, 0), (fun))) > > > > > > > > Do you agree? > > > > > > The Function (fun) case is the easy one: the value is not split in two. > > > > > > But look at the entity case, it's split in two: > > > > > > FIELD_PREP(BIT(21), FIELD_GET(BIT(6), (ent))) FIELD_PREP(GENMASK(12, 7), > > > FIELD_GET(GENMASK(5, 0), (ent))) > > > > > > same for control > > > > > > FIELD_PREP(GENMASK(20, 19), FIELD_GET(GENMASK(5, 4), (ctl))) | > > > FIELD_PREP(GENMASK(6, 3), FIELD_GET(GENMASK(3, 0), (ctl))) | > > > > > > and same for channel number > > > > > > FIELD_PREP(GENMASK(17, 15), FIELD_GET(GENMASK(5, 3), (ch))) | > > > FIELD_PREP(GENMASK(2, 0), FIELD_GET(GENMASK(2, 0), (ch)))) > > > > > > I don't see how we can avoid using the FIELD_GET to extract the relevant > > > bits from entity, control, channel number values. > > > > No, you dont need FIELD_GET, that would be pointless for this helper if > > that was the case > > I don't get how one would specify which parts of the original value are > extracted? > > > > > > > > > Or I am missing your point completely. > > > > Correct > > > > It should be: > > > > foo |= u32_encode_bits(val, FOO_MASK_A); > > > > which would write val into bits represented by FOO_MASK_A by > > appropriately shifting val and masking it with FOO_MASK_A > > > > So net result is bits in FOO_MASK_A are modified with val, rest of the > > bits are not touched > > Vinod, please see the explanation below [1], we need to split the original > value in two and insert the bits in two separate locations. > > You only considered the simple case for the functions, your proposal will > not work for entities, controls and channel numbers. > > > > > > > > > > > > > And while at it, consider defining masks for various fields rather than > > > > > > using numbers in GENMASK() above, that would look better, be more > > > > > > readable and people can reuse it. > > > > > > > > > > Actually on this one I disagree. These fields are not intended to be used by > > > > > anyone, the goal is precisely to hide them behind regmap, and the use of raw > > > > > numbers makes it easier to cross-check the documentation and the code. > > > > > Adding a separate set of definitions would not increase readability. > > > > > > > > Which one would you prefer: > > > > > > > > #define SDCA_FUN_MASK GENMASK(24, 22) > > > > > > > > foo |= u32_encode_bits(SDCA_FUN_MASK, fun) > > > > > > > > Or the one proposed...? > > > > > > Same as above, let's see what this does with the control case where we'd > > > need to have four definitions: > > [1] > > > > > > > #define SDCA_CONTROL_DEST_MASK1 GENMASK(20, 19) > > > #define SDCA_CONTROL_ORIG_MASK1 GENMASK(5, 4) > > > #define SDCA_CONTROL_DEST_MASK2 GENMASK(6, 3) > > > #define SDCA_CONTROL_ORIG_MASK2 GENMASK(3, 0) I think I missed ORIG and DEST stuff, what does this mean here? Relooking at the bit definition, for example 'Control Number' is defined in both 17:15 as well as 2:0, why is that. Is it split? How does one program a control number into this? > > > > > > And the code would look like > > > > > > foo |= u32_encode_bits(SDCA_CONTROL_DEST_MASK1, > > > FIELD_GET(SDCA_CONTROL_ORIG_MASK1, fun)); > > > foo |= u32_encode_bits(SDCA_CONTROL_DEST_MASK2, > > > FIELD_GET(SDCA_CONTROL_ORIG_MASK2, fun)); > > > > > > The original suggestion was: > > > > > > FIELD_PREP(GENMASK(20, 19), FIELD_GET(GENMASK(5, 4), (ctl))) | > > > FIELD_PREP(GENMASK(6, 3), FIELD_GET(GENMASK(3, 0), (ctl))) | > > > > > > I prefer the original... Adding these defines doesn't really add value > > > because > > > a) the values will not be reused anywhere else. > > > b) we need 12 of those defines > > > b) we need a prefix for those defines which makes the code heavier > > -- ~Vinod
