Commit f6df1aa6 authored by Christo du Toit's avatar Christo du Toit Committed by Jakub Kicinski
Browse files

nfp: remove pessimistic NFP_QCP_MAX_ADD limits 



Multiple writes cause intermediate pointer values that do not
end on complete TX descriptors.

The QCP peripheral on the NFP provides a number of access
modes.  In some access modes, the maximum amount to add must
be restricted to a 6bit value.  The particular access mode
used by _nfp_qcp_ptr_add() has no such restrictions, so the
"< NFP_QCP_MAX_ADD" test is unnecessary.

Note that trying to add more that the configured ring size
in a single add will cause a QCP overflow, caught and handled
by the QCP peripheral.

Signed-off-by: default avatarChristo du Toit <christo.du.toit@netronome.com>
Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarFei Qin <fei.qin@corigine.com>
Signed-off-by: default avatarSimon Horman <simon.horman@corigine.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 940ea0ea

drivers/net/ethernet/netronome/nfp/nfp_net.h

+2 −30
Original line number Diff line number Diff line
@@ -814,41 +814,15 @@ enum nfp_qcp_ptr { 
	NFP_QCP_WRITE_PTR

};



/* There appear to be an *undocumented* upper limit on the value which

 * one can add to a queue and that value is either 0x3f or 0x7f.  We

 * go with 0x3f as a conservative measure.

 */

#define NFP_QCP_MAX_ADD				0x3f



static inline void _nfp_qcp_ptr_add(u8 __iomem *q,

				    enum nfp_qcp_ptr ptr, u32 val)

{

	u32 off;



	if (ptr == NFP_QCP_READ_PTR)

		off = NFP_QCP_QUEUE_ADD_RPTR;

	else

		off = NFP_QCP_QUEUE_ADD_WPTR;



	while (val > NFP_QCP_MAX_ADD) {

		writel(NFP_QCP_MAX_ADD, q + off);

		val -= NFP_QCP_MAX_ADD;

	}



	writel(val, q + off);

}



/**

 * nfp_qcp_rd_ptr_add() - Add the value to the read pointer of a queue

 *

 * @q:   Base address for queue structure

 * @val: Value to add to the queue pointer

 *

 * If @val is greater than @NFP_QCP_MAX_ADD multiple writes are performed.

 */

static inline void nfp_qcp_rd_ptr_add(u8 __iomem *q, u32 val)

{

	_nfp_qcp_ptr_add(q, NFP_QCP_READ_PTR, val);

	writel(val, q + NFP_QCP_QUEUE_ADD_RPTR);

}



/**
@@ -856,12 +830,10 @@ static inline void nfp_qcp_rd_ptr_add(u8 __iomem *q, u32 val) 
 *

 * @q:   Base address for queue structure

 * @val: Value to add to the queue pointer

 *

 * If @val is greater than @NFP_QCP_MAX_ADD multiple writes are performed.

 */

static inline void nfp_qcp_wr_ptr_add(u8 __iomem *q, u32 val)

{

	_nfp_qcp_ptr_add(q, NFP_QCP_WRITE_PTR, val);

	writel(val, q + NFP_QCP_QUEUE_ADD_WPTR);

}



static inline u32 _nfp_qcp_read(u8 __iomem *q, enum nfp_qcp_ptr ptr)