Commit 8730f45d authored by Alex Elder's avatar Alex Elder Committed by David S. Miller
Browse files

net: ipa: program metadata mask differently 



The way the mask value is programmed for QMAP RX endpoints was based
on some wrong assumptions about the way metadata containing the QMAP
mux_id value is formatted.  The metadata value supplied by the
modem is *not* in QMAP format, and in fact contains the mux_id we
want in its (big endian) low-order byte.  That byte must be written
by the IPA into offset 1 of the QMAP header it inserts before the
received packet.

QMAP TX endpoints *do* use a QMAP header as the metadata sent with
each packet.  The modem assumes this, and based on that assumes the
mux_id is in the second byte.  To match those assumptions we must
program the modem TX (QMAP) endpoint HDR register to indicate the
metadata will be found at offset 0 in the message header.

The previous configuration managed to work, but it was not working
correctly.  This patch fixes a bug whose symptom was receipt of
messages containing the wrong QMAP mux_id.

In fixing this, get rid of ipa_rmnet_mux_id_metadata_mask(), which
was more or less defined so there was a separate place to explain
what was happening as we generated the mask value.  Instead, put a
longer description of how this works above ipa_endpoint_init_hdr(),
and define the metadata mask to use as a simple constant.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c25cba36

drivers/net/ipa/ipa_endpoint.c

+39 −33
Original line number Diff line number Diff line
@@ -32,6 +32,9 @@ 
/* The amount of RX buffer space consumed by standard skb overhead */

#define IPA_RX_BUFFER_OVERHEAD	(PAGE_SIZE - SKB_MAX_ORDER(NET_SKB_PAD, 0))



/* Where to find the QMAP mux_id for a packet within modem-supplied metadata */

#define IPA_ENDPOINT_QMAP_METADATA_MASK		0x000000ff /* host byte order */



#define IPA_ENDPOINT_RESET_AGGR_RETRY_MAX	3

#define IPA_AGGR_TIME_LIMIT_DEFAULT		1000	/* microseconds */
@@ -433,6 +436,24 @@ static void ipa_endpoint_init_cfg(struct ipa_endpoint *endpoint) 
	iowrite32(val, endpoint->ipa->reg_virt + offset);

}



/**

 * We program QMAP endpoints so each packet received is preceded by a QMAP

 * header structure.  The QMAP header contains a 1-byte mux_id and 2-byte

 * packet size field, and we have the IPA hardware populate both for each

 * received packet.  The header is configured (in the HDR_EXT register)

 * to use big endian format.

 *

 * The packet size is written into the QMAP header's pkt_len field.  That

 * location is defined here using the HDR_OFST_PKT_SIZE field.

 *

 * The mux_id comes from a 4-byte metadata value supplied with each packet

 * by the modem.  It is *not* a QMAP header, but it does contain the mux_id

 * value that we want, in its low-order byte.  A bitmask defined in the

 * endpoint's METADATA_MASK register defines which byte within the modem

 * metadata contains the mux_id.  And the OFST_METADATA field programmed

 * here indicates where the extracted byte should be placed within the QMAP

 * header.

 */

static void ipa_endpoint_init_hdr(struct ipa_endpoint *endpoint)

{

	u32 offset = IPA_REG_ENDP_INIT_HDR_N_OFFSET(endpoint->endpoint_id);
@@ -441,25 +462,31 @@ static void ipa_endpoint_init_hdr(struct ipa_endpoint *endpoint) 
	if (endpoint->data->qmap) {

		size_t header_size = sizeof(struct rmnet_map_header);



		/* We might supply a checksum header after the QMAP header */

		if (endpoint->toward_ipa && endpoint->data->checksum)

			header_size += sizeof(struct rmnet_map_ul_csum_header);



		val |= u32_encode_bits(header_size, HDR_LEN_FMASK);

		/* metadata is the 4 byte rmnet_map header itself */

		val |= HDR_OFST_METADATA_VALID_FMASK;

		val |= u32_encode_bits(0, HDR_OFST_METADATA_FMASK);

		/* HDR_ADDITIONAL_CONST_LEN is 0; (IPA->AP only) */



		/* Define how to fill mux_id in a received QMAP header */

		if (!endpoint->toward_ipa) {

			u32 size_offset = offsetof(struct rmnet_map_header,

						   pkt_len);

			u32 off;	/* Field offset within header */



			/* Where IPA will write the metadata value */

			off = offsetof(struct rmnet_map_header, mux_id);

			val |= u32_encode_bits(off, HDR_OFST_METADATA_FMASK);



			/* Where IPA will write the length */

			off = offsetof(struct rmnet_map_header, pkt_len);

			val |= HDR_OFST_PKT_SIZE_VALID_FMASK;

			val |= u32_encode_bits(size_offset,

					       HDR_OFST_PKT_SIZE_FMASK);

			val |= u32_encode_bits(off, HDR_OFST_PKT_SIZE_FMASK);

		}

		/* For QMAP TX, metadata offset is 0 (modem assumes this) */

		val |= HDR_OFST_METADATA_VALID_FMASK;



		/* HDR_ADDITIONAL_CONST_LEN is 0; (RX only) */

		/* HDR_A5_MUX is 0 */

		/* HDR_LEN_INC_DEAGG_HDR is 0 */

		/* HDR_METADATA_REG_VALID is 0; (AP->IPA only) */

		/* HDR_METADATA_REG_VALID is 0 (TX only) */

	}



	iowrite32(val, endpoint->ipa->reg_virt + offset);
@@ -482,28 +509,6 @@ static void ipa_endpoint_init_hdr_ext(struct ipa_endpoint *endpoint) 
	iowrite32(val, endpoint->ipa->reg_virt + offset);

}



/**

 * Generate a metadata mask value that will select only the mux_id

 * field in an rmnet_map header structure.  The mux_id is at offset

 * 1 byte from the beginning of the structure, but the metadata

 * value is treated as a 4-byte unit.  So this mask must be computed

 * with endianness in mind.  Note that ipa_endpoint_init_hdr_metadata_mask()

 * will convert this value to the proper byte order.

 *

 * Marked __always_inline because this is really computing a

 * constant value.

 */

static __always_inline __be32 ipa_rmnet_mux_id_metadata_mask(void)

{

	size_t mux_id_offset = offsetof(struct rmnet_map_header, mux_id);

	u32 mux_id_mask = 0;

	u8 *bytes;



	bytes = (u8 *)&mux_id_mask;

	bytes[mux_id_offset] = 0xff;	/* mux_id is 1 byte */



	return cpu_to_be32(mux_id_mask);

}



static void ipa_endpoint_init_hdr_metadata_mask(struct ipa_endpoint *endpoint)

{
@@ -513,8 +518,9 @@ static void ipa_endpoint_init_hdr_metadata_mask(struct ipa_endpoint *endpoint) 


	offset = IPA_REG_ENDP_INIT_HDR_METADATA_MASK_N_OFFSET(endpoint_id);



	/* Note that HDR_ENDIANNESS indicates big endian header fields */

	if (!endpoint->toward_ipa && endpoint->data->qmap)

		val = ipa_rmnet_mux_id_metadata_mask();

		val = cpu_to_be32(IPA_ENDPOINT_QMAP_METADATA_MASK);



	iowrite32(val, endpoint->ipa->reg_virt + offset);

}

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