Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752524AbbBWOKz (ORCPT ); Mon, 23 Feb 2015 09:10:55 -0500 Received: from mail-oi0-f53.google.com ([209.85.218.53]:64507 "EHLO mail-oi0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752336AbbBWOKy (ORCPT ); Mon, 23 Feb 2015 09:10:54 -0500 Message-ID: <54EB34E7.7060400@monstr.eu> Date: Mon, 23 Feb 2015 15:10:47 +0100 From: Michal Simek Reply-To: monstr@monstr.eu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Arun Chandran CC: Nicolas Ferre , netdev , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] net: macb: Add big endian CPU support References: <1424258975-28611-1-git-send-email-achandran@mvista.com> <54E5D5A0.90005@monstr.eu> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="alJgH8kUUJFG8Jqxd5A4CB0g0aPQILODU" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5243 Lines: 153 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --alJgH8kUUJFG8Jqxd5A4CB0g0aPQILODU Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi Arun, On 02/20/2015 12:45 PM, Arun Chandran wrote: > On Thu, Feb 19, 2015 at 5:52 PM, Michal Simek wrote:= >> >> On 02/18/2015 12:29 PM, Arun Chandran wrote: >>> This patch converts all __raw_readl and __raw_writel function calls >>> to their corresponding readl_relaxed and writel_relaxed variants. >>> >>> It also tells the driver to set ahb_endian_swp_mgmt_en bit in dma_cfg= >>> when the CPU is configured in big endian mode. >>> >>> Signed-off-by: Arun Chandran >>> --- >>> This patch is tested on xilinx ZC702 evaluation board with >>> CONFIG_CPU_BIG_ENDIAN=3Dy and booting NFS rootfs >>> --- >>> --- >>> drivers/net/ethernet/cadence/macb.c | 18 ++++++++++++------ >>> drivers/net/ethernet/cadence/macb.h | 15 ++++++++------- >>> 2 files changed, 20 insertions(+), 13 deletions(-) >>> >>> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethern= et/cadence/macb.c >>> index ad76b8e..05fb36d 100644 >>> --- a/drivers/net/ethernet/cadence/macb.c >>> +++ b/drivers/net/ethernet/cadence/macb.c >>> @@ -449,7 +449,7 @@ static void macb_update_stats(struct macb *bp) >>> WARN_ON((unsigned long)(end - p - 1) !=3D (MACB_TPF - MACB_PFR)= / 4); >>> >>> for(; p < end; p++, reg++) >>> - *p +=3D __raw_readl(reg); >>> + *p +=3D readl_relaxed(reg); >>> } >>> >>> static int macb_halt_tx(struct macb *bp) >>> @@ -1585,7 +1585,11 @@ static void macb_configure_dma(struct macb *bp= ) >>> if (bp->dma_burst_length) >>> dmacfg =3D GEM_BFINS(FBLDO, bp->dma_burst_lengt= h, dmacfg); >>> dmacfg |=3D GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L); >>> - dmacfg &=3D ~GEM_BIT(ENDIA); >>> + dmacfg &=3D ~GEM_BIT(ENDIA_PKT); >>> + /* Tell the chip to byteswap descriptors on big-endian = hosts */ >>> +#ifdef __BIG_ENDIAN >>> + dmacfg |=3D GEM_BIT(ENDIA_DESC); >>> +#endif >> >> I don't think this is the best way what you should do. >> Instead of having this ifdef here you should find out any reg and dete= ct if the IP >> is in big endian or little endian mode. I have done it for some xilinx= IPs which >> can run on big or little endian system. >> In general find reg which some field which has some meaning - write th= ere 1 >> and read expected value and based on that decide if you are on big or = little endian system. >=20 > Hi Michal, >=20 > I was not able to find any such registers for GEM in the TRM > http://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000= -TRM.pdf >=20 > I tried writing to dma_cfg (0x00000010) and reading from design_cfg5 > (0x00000290) > Its not reflecting anything(design_cfg5 always reads same value); It > is not helping. >=20 > The only way (I don't think its not right way either) I can think of > eliminating that > #ifdef __BIG_ENDIAN is reading some register in ARM cpu to identify it= s > current endianness and write dma_cfg accordingly. Definitely no to detect cpu endianess. What about this? writel(0x2, 0xE000b000); //write little endian if (readl(0xE000b000) =3D=3D 0x2) { //read little endian printf("little endian\n") disable 0x2 bit (loopback) } else { printf("big endian\n"); definitely good to check writing 0x2 here that IP is in big endian and reacts - if not BUG() } I have written this to spi-xilinx.c and you can use similar construction for macb too (of course with checking above). /* * Detect endianess on the IP via loop bit in CR. Detection * must be done before reset is sent because incorrect reset * value generates error interrupt. * Setup little endian helper functions first and try to use them * and check if bit was correctly setup or not. */ xspi->read_fn =3D xspi_read32; xspi->write_fn =3D xspi_write32; xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET); tmp =3D xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); tmp &=3D XSPI_CR_LOOP; if (tmp !=3D XSPI_CR_LOOP) { xspi->read_fn =3D xspi_read32_be; xspi->write_fn =3D xspi_write32_be; } Thanks, Michal --=20 Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform --alJgH8kUUJFG8Jqxd5A4CB0g0aPQILODU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAlTrNOcACgkQykllyylKDCGkMQCfS8/5arlQvJj+jBSoRG+NESQI 0U4AnA50DzGU9wT2TvjsBa4LE2JPtSV+ =UkW/ -----END PGP SIGNATURE----- --alJgH8kUUJFG8Jqxd5A4CB0g0aPQILODU-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/