From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 10/10] esp: enable CONFIG2_FENAB for am53c974 Date: Fri, 21 Nov 2014 11:22:46 +0100 Message-ID: <546F1276.9000704@suse.de> References: <1416562077-105715-1-git-send-email-hare@suse.de> <1416562077-105715-11-git-send-email-hare@suse.de> <546F0F2B.40901@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:48254 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754324AbaKUKWw (ORCPT ); Fri, 21 Nov 2014 05:22:52 -0500 In-Reply-To: <546F0F2B.40901@redhat.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Paolo Bonzini , James Bottomley Cc: Christoph Hellwig , linux-scsi@vger.kernel.org On 11/21/2014 11:08 AM, Paolo Bonzini wrote: >=20 >=20 > On 21/11/2014 10:27, Hannes Reinecke wrote: >> CONFIG2_FENAB ('feature enable') changed definition between chip >> revisions, from 'Latch SCSI Phase' to 'Latch SCSI Phase, display >> chip ID upon reset, and enable 24 bit addresses'. >> So only enable it for am53c974 where we know what it's doing. >> >> Signed-off-by: Hannes Reinecke >> --- >> drivers/scsi/am53c974.c | 30 ++++++++++++++++++++++++++++++ >> drivers/scsi/esp_scsi.c | 4 ++++ >> 2 files changed, 34 insertions(+) >> >> diff --git a/drivers/scsi/am53c974.c b/drivers/scsi/am53c974.c >> index 0452ed1..722e781 100644 >> --- a/drivers/scsi/am53c974.c >> +++ b/drivers/scsi/am53c974.c >> @@ -252,6 +252,8 @@ static void pci_esp_send_dma_cmd(struct esp *esp= , u32 addr, u32 esp_count, >> =20 >> pci_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW); >> pci_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED); >> + if (esp->config2 & ESP_CONFIG2_FENAB) >> + pci_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI); >=20 > Why do this conditionally? We know that FENAB is true here, don't we= ? >=20 > (Maybe I'm missing something obvious though). >=20 Not really. Point is that 'FENAB' does actually three things: - Enable TCHI for 24-bit DMA transfer lengths - Provide Chip ID in TCHI after reset - Latch SCSI phase after completion in SCSI STATUS So we _might_ run into timing issues due to the last point, so I've made it conditional in case we'd have to disable it. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 21284 (AG N=FCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html