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Message-ID: <d9459776-f3a8-2d97-283a-c50e1c41c4f5@gmail.com>
Date: Fri, 8 Mar 2019 17:26:13 -0800
From: Steve Longerbeam <slongerbeam@...il.com>
To: Philipp Zabel <p.zabel@...gutronix.de>, linux-media@...r.kernel.org
Cc: Tim Harvey <tharvey@...eworks.com>,
"open list:DRM DRIVERS FOR FREESCALE IMX"
<dri-devel@...ts.freedesktop.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 5/7] gpu: ipu-v3: ipu-ic: Add support for limited range
encoding
On 3/8/19 3:57 AM, Philipp Zabel wrote:
> On Thu, 2019-03-07 at 15:33 -0800, Steve Longerbeam wrote:
>> Add support for the following conversions:
>>
>> - YUV full-range to YUV limited-range
>> - YUV limited-range to YUV full-range
>> - YUV limited-range to RGB full-range
>> - RGB full-range to YUV limited-range
>>
>> The last two conversions require operating on the YUV full-range
>> encoding and inverse encoding coefficients, with the YUV-to-YUV
>> limited<->full coefficients. The formula to convert is
>>
>> M_c = M_a * M_b
>> O_c = M_a * O_b + O_a
>>
>> For calculating the RGB full-range to YUV limited-range coefficients:
>>
>> [M_a, O_a] = YUV full-range to YUV limited-range coefficients.
>> [M_b, O_b] = RGB full-range to YUV full-range coefficients.
>>
>> For calculating the YUV limited-range to RGB full-range coefficients:
>>
>> [M_a, O_a] = YUV full-range to RGB full-range coefficients.
>> [M_b, O_b] = YUV limited-range to YUV full-range coefficients.
>>
>> The calculation of [M_c, O_c] is carried out by the function
>> transform_coeffs().
>>
>> In the future if RGB limited range encoding is required, the same
>> function can be used. And cascaded to create all combinations of
>> encoding for YUV limited/full range <-> RGB limited/full range,
>> passing the output coefficients from one call as the input for the
>> next.
>>
>> For example, to create YUV full-range to RGB limited-range coefficients:
>>
>> [M_a, O_a] = RGB full-range to RGB limited-range coefficients.
>> [M_b, O_b] = YUV full-range to RGB full-range coefficients.
>>
>> and that output sent as input to create YUV limited-range to RGB
>> limited-range coefficients:
>>
>> [M_a, O_a] = YUV full-range to RGB limited-range coefficients.
>> [M_b, O_b] = YUV limited-range to YUV full-range coefficients.
>>
>> Signed-off-by: Steve Longerbeam <slongerbeam@...il.com>
> I'm not a big fan of this. Wouldn't it be much easier to compute all
> necessary task parameter sets offline with high precision, and store the
> precomputed sets in the compact representation?
I am thinking of when support might be added for the other encoding
standards. With this transform function, only two new task parameter
structs need to be added, one for yuv-full-to-rgb-full, and one for
rgb-full-to-yuv-full. Without transform_coeffs(), four structs would
have to be added (adding encoding to and from yuv-limited). And if
rgb-limited support is added, it would mean a total of eight new structs
for a new encoding standard. But with transform_coeffs(), still only the
two structs above are needed, and the function would compute the others
automatically in runtime.
Steve
>
>
>> ---
>> drivers/gpu/ipu-v3/ipu-ic.c | 281 +++++++++++++++++++++++++++++++++---
>> 1 file changed, 263 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/gpu/ipu-v3/ipu-ic.c b/drivers/gpu/ipu-v3/ipu-ic.c
>> index 1460901af9b5..a7dd85f8d832 100644
>> --- a/drivers/gpu/ipu-v3/ipu-ic.c
>> +++ b/drivers/gpu/ipu-v3/ipu-ic.c
>> @@ -178,10 +178,10 @@ static inline void ipu_ic_write(struct ipu_ic *ic, u32 value, unsigned offset)
>> }
>>
>> struct ic_encode_coeff {
>> - s16 coeff[3][3]; /* signed 9-bit integer coefficients */
>> - s16 offset[3]; /* signed 11+2-bit fixed point offset */
>> - u8 scale:2; /* scale coefficients * 2^(scale-1) */
>> - bool sat:1; /* saturate to (16, 235(Y) / 240(U, V)) */
>> + int coeff[3][3]; /* signed 9-bit integer coefficients */
>> + int offset[3]; /* signed 13-bit integer offset */
>> + int scale; /* scale coefficients * 2^(scale-1) */
>> + bool sat; /* saturate to (16, 235(Y) / 240(U, V)) */
>> };
>>
>> /*
>> @@ -277,6 +277,231 @@ static const struct ic_encode_coeff ic_encode_ycbcr2rgb_709 = {
>> .scale = 2,
>> };
>>
>> +/*
>> + * YUV full range to YUV limited range:
>> + *
>> + * Y_lim = 0.8588 * Y_full + 16
>> + * Cb_lim = 0.8784 * (Cb_full - 128) + 128
>> + * Cr_lim = 0.8784 * (Cr_full - 128) + 128
>> + */
>> +static const struct ic_encode_coeff ic_encode_ycbcr_full2lim = {
>> + .coeff = {
>> + { 219, 0, 0 },
>> + { 0, 224, 0 },
>> + { 0, 0, 224 },
>> + },
>> + .offset = { 64, 62, 62 },
>> + .scale = 1,
>> +};
>> +
>> +/*
>> + * YUV limited range to YUV full range:
>> + *
>> + * Y_full = 1.1644 * (Y_lim - 16)
>> + * Cb_full = 1.1384 * (Cb_lim - 128) + 128
>> + * Cr_full = 1.1384 * (Cr_lim - 128) + 128
>> + */
>> +static const struct ic_encode_coeff ic_encode_ycbcr_lim2full = {
>> + .coeff = {
>> + { 149, 0, 0 },
>> + { 0, 145, 0 },
>> + { 0, 0, 145 },
>> + },
>> + .offset = { -37, -35, -35 },
>> + .scale = 2,
>> +};
>> +
>> +/*
>> + * RGB full range to RGB limited range:
>> + *
>> + * R_lim = 0.8588 * R_full + 16
>> + * G_lim = 0.8588 * G_full + 16
>> + * B_lim = 0.8588 * B_full + 16
>> + */
>> +static const struct ic_encode_coeff
>> +ic_encode_rgb_full2lim __maybe_unused = {
>> + .coeff = {
>> + { 220, 0, 0 },
>> + { 0, 220, 0 },
>> + { 0, 0, 220 },
>> + },
>> + .offset = { 64, 64, 64 },
>> + .scale = 1,
>> +};
>> +
>> +/*
>> + * RGB limited range to RGB full range:
>> + *
>> + * R_full = 1.1644 * (R_lim - 16)
>> + * G_full = 1.1644 * (G_lim - 16)
>> + * B_full = 1.1644 * (B_lim - 16)
>> + */
>> +static const struct ic_encode_coeff
>> +ic_encode_rgb_lim2full __maybe_unused = {
>> + .coeff = {
>> + { 149, 0, 0 },
>> + { 0, 149, 0 },
>> + { 0, 0, 149 },
>> + },
>> + .offset = { -37, -37, -37 },
>> + .scale = 2,
>> +};
>> +
>> +/*
>> + * Convert a coefficient and scale value in TPMEM register format
>> + * to a signed int times 256 (fix the radix point). The TPMEM register
>> + * coefficient format is a signed 9-bit value (sign bit at bit 8,
>> + * mantissa = coeff * 2 ^ (8 - scale - 1)).
>> + */
>> +static int coeff_fix(int coeff, int scale)
>> +{
>> + if (coeff >= 256)
>> + coeff -= 512;
>> + if (scale == 0)
>> + return DIV_ROUND_CLOSEST(coeff, 2);
>> + return coeff << (scale - 1);
>> +}
>> +
>> +/*
>> + * Convert a signed int coefficient times 256 to TPMEM register
>> + * format, given a scale value = TPMEM scale - 1.
>> + */
>> +static int coeff_normalize(int coeff, int scale)
>> +{
>> + coeff = DIV_ROUND_CLOSEST(coeff, 1 << scale);
>> + if (coeff < 0)
>> + coeff += 512;
>> + return coeff;
>> +}
>> +
>> +/*
>> + * Convert an offset and scale value in TPMEM register format to a
>> + * signed int times 256 (fix the radix point). The TPMEM register
>> + * offset format is a signed 13-bit value (sign bit at bit 12,
>> + * mantissa = offset * 2 ^ (2 - (scale - 1)).
>> + */
>> +static int offset_fix(int offset, int scale)
>> +{
>> + return offset << (8 - (2 - (scale - 1)));
>> +}
>> +
>> +/*
>> + * Convert a signed int offset times 256 to TPMEM register
>> + * format, given a scale value = TPMEM scale - 1.
>> + */
>> +static int offset_normalize(int off, int scale)
>> +{
>> + return DIV_ROUND_CLOSEST(off, 1 << (8 - (2 - scale)));
>> +}
>> +
>> +/*
>> + * Find the scale value that fits the given coefficient within
>> + * the 8-bit TPMEM mantissa.
>> + */
>> +static int get_coeff_scale(int coeff)
>> +{
>> + int scale = 0;
>> +
>> + while (abs(coeff) >= 256 && scale <= 2) {
>> + coeff = DIV_ROUND_CLOSEST(coeff, 2);
>> + scale++;
>> + }
>> +
>> + return scale;
>> +}
>> +
>> +/*
>> + * The above defined encoding coefficients all encode between
>> + * full-range RGB and full-range YCbCr.
>> + *
>> + * This function calculates a matrix M_c and offset vector O_c, given
>> + * input matrices M_a, M_b and offset vectors O_a, O_b, such that:
>> + *
>> + * M_c = M_a * M_b
>> + * O_c = M_a * O_b + O_a
>> + *
>> + * This operation will transform the full-range coefficients to
>> + * coefficients that encode to or from limited range YCbCr or RGB.
>> + *
>> + * For example, to transform ic_encode_rgb2ycbcr_601 to encode to
>> + * limited-range YCbCr:
>> + *
>> + * [M_a, O_a] = ic_encode_ycbcr_full2lim
>> + * [M_b, O_b] = ic_encode_rgb2ycbcr_601
>> + *
>> + * To transform the inverse coefficients ic_encode_ycbcr2rgb_601 to
>> + * encode from limited-range YCbCr:
>> + *
>> + * [M_a, O_a] = ic_encode_ycbcr2rgb_601
>> + * [M_b, O_b] = ic_encode_ycbcr_lim2full
>> + *
>> + * The function can also be used to create RGB limited range
>> + * coefficients, and cascaded to create all combinations of
>> + * encodings between YCbCr limited/full range <-> RGB limited/full
>> + * range.
>> + */
>> +static void transform_coeffs(struct ic_encode_coeff *out,
>> + const struct ic_encode_coeff *a,
>> + const struct ic_encode_coeff *b)
>> +{
>> + int c_a, c_b, c_out;
>> + int o_a, o_b, o_out;
>> + int outscale = 0;
>> + int i, j, k;
>> +
>> + for (i = 0; i < 3; i++) {
>> + o_out = 0;
>> + for (j = 0; j < 3; j++) {
>> + int scale;
>> +
>> + /* M_c[i,j] = M_a[i,k] * M_b[k,j] */
>> + c_out = 0;
>> + for (k = 0; k < 3; k++) {
>> + c_a = coeff_fix(a->coeff[i][k], a->scale);
>> + c_b = coeff_fix(b->coeff[k][j], b->scale);
>> + c_out += c_a * c_b;
>> + }
>> +
>> + c_out = DIV_ROUND_CLOSEST(c_out, 1 << 8);
>> + out->coeff[i][j] = c_out;
>> +
>> + /*
>> + * get scale for this coefficient and update
>> + * final output scale.
>> + */
>> + scale = get_coeff_scale(c_out);
>> + outscale = max(outscale, scale);
>> +
>> + /* M_a[i,j] * O_b[j] */
>> + c_a = coeff_fix(a->coeff[i][j], a->scale);
>> + o_b = offset_fix(b->offset[j], b->scale);
>> + o_out += DIV_ROUND_CLOSEST(c_a * o_b, 1 << 8);
>> + }
>> +
>> + /* O_c[i] = (M_a * O_b)[i] + O_a[i] */
>> + o_a = offset_fix(a->offset[i], a->scale);
>> + o_out += o_a;
>> +
>> + out->offset[i] = o_out;
>> + }
>> +
>> + /*
>> + * normalize output coefficients and offsets to TPMEM
>> + * register format.
>> + */
>> + for (i = 0; i < 3; i++) {
>> + for (j = 0; j < 3; j++) {
>> + c_out = out->coeff[i][j];
>> + out->coeff[i][j] = coeff_normalize(c_out, outscale);
>> + }
>> +
>> + o_out = out->offset[i];
>> + out->offset[i] = offset_normalize(o_out, outscale);
>> + }
>> +
>> + out->scale = outscale + 1;
>> +}
>> +
>> static int calc_csc_coeffs(struct ipu_ic_priv *priv,
>> struct ic_encode_coeff *coeff_out,
>> const struct ipu_ic_colorspace *in,
>> @@ -290,14 +515,6 @@ static int calc_csc_coeffs(struct ipu_ic_priv *priv,
>> return -ENOTSUPP;
>> }
>>
>> - if ((in->cs == IPUV3_COLORSPACE_YUV &&
>> - in->quant != V4L2_QUANTIZATION_FULL_RANGE) ||
>> - (out->cs == IPUV3_COLORSPACE_YUV &&
>> - out->quant != V4L2_QUANTIZATION_FULL_RANGE)) {
>> - dev_err(priv->ipu->dev, "Limited range YUV not supported\n");
>> - return -ENOTSUPP;
>> - }
>> -
>> if ((in->cs == IPUV3_COLORSPACE_RGB &&
>> in->quant != V4L2_QUANTIZATION_FULL_RANGE) ||
>> (out->cs == IPUV3_COLORSPACE_RGB &&
>> @@ -307,7 +524,18 @@ static int calc_csc_coeffs(struct ipu_ic_priv *priv,
>> }
>>
>> if (in->cs == out->cs) {
>> - *coeff_out = ic_encode_identity;
>> + if (in->quant == out->quant) {
>> + *coeff_out = ic_encode_identity;
>> + } else if (in->quant == V4L2_QUANTIZATION_FULL_RANGE) {
>> + /* YUV full-range to YUV limited-range */
>> + *coeff_out = ic_encode_ycbcr_full2lim;
>> +
>> + /* set saturation bit for YUV limited-range output */
>> + coeff_out->sat = true;
>> + } else {
>> + /* YUV limited-range to YUV full-range */
>> + *coeff_out = ic_encode_ycbcr_lim2full;
>> + }
>>
>> return 0;
>> }
>> @@ -328,7 +556,24 @@ static int calc_csc_coeffs(struct ipu_ic_priv *priv,
>> return -ENOTSUPP;
>> }
>>
>> - *coeff_out = *encode_coeff;
>> + if (in->quant == out->quant) {
>> + /*
>> + * YUV full-range to RGB full-range, or
>> + * RGB full-range to YUV full-range.
>> + */
>> + *coeff_out = *encode_coeff;
>> + } else if (inverse_encode) {
>> + /* YUV limited-range to RGB full-range */
>> + transform_coeffs(coeff_out, encode_coeff,
>> + &ic_encode_ycbcr_lim2full);
>> + } else {
>> + /* RGB full-range to YUV limited-range */
>> + transform_coeffs(coeff_out, &ic_encode_ycbcr_full2lim,
>> + encode_coeff);
>> +
>> + /* set saturation bit for YUV limited-range output */
>> + coeff_out->sat = true;
>> + }
>>
>> return 0;
>> }
>> @@ -340,9 +585,9 @@ static int init_csc(struct ipu_ic *ic,
>> {
>> struct ipu_ic_priv *priv = ic->priv;
>> struct ic_encode_coeff coeff;
>> + const unsigned int (*c)[3];
>> + const unsigned int *a;
>> u32 __iomem *base;
>> - const u16 (*c)[3];
>> - const u16 *a;
>> u32 param;
>> int ret;
>>
>> @@ -354,8 +599,8 @@ static int init_csc(struct ipu_ic *ic,
>> (priv->tpmem_base + ic->reg->tpmem_csc[csc_index]);
>>
>> /* Cast to unsigned */
>> - c = (const u16 (*)[3])coeff.coeff;
>> - a = (const u16 *)coeff.offset;
>> + c = (const unsigned int (*)[3])coeff.coeff;
>> + a = (const unsigned int *)coeff.offset;
>>
>> param = ((a[0] & 0x1f) << 27) | ((c[0][0] & 0x1ff) << 18) |
>> ((c[1][1] & 0x1ff) << 9) | (c[2][2] & 0x1ff);
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